Medicine – Urea and Creatinine

Urea and creatinine are commonly measured blood markers used to assess kidney function, but neither is a perfect measure of glomerular filtration on its own. Their interpretation depends on factors such as muscle mass, hydration, protein intake, liver function, drugs and pregnancy.

A useful distinction is that creatinine is strongly influenced by muscle metabolism, whereas urea is strongly influenced by protein metabolism, hydration and liver function.

1. Creatinine

Creatinine is produced from the breakdown of:

Creatine in skeletal muscle.

It is released into the blood at a relatively steady rate and is eliminated mainly by:

Glomerular filtration.

A small amount is also:

Secreted by the proximal tubule.

Because of this, serum creatinine is commonly used as a marker of renal filtration.

2. Raised Creatinine – Reduced GFR

The most important cause of a raised creatinine is:

Reduced glomerular filtration rate.

This may occur in:

Acute kidney injury.

Chronic kidney disease.

Pre-renal hypoperfusion.

Intrinsic renal disease.

Post-renal obstruction.

Therefore:

RISING CREATININE → THINK REDUCED GFR FIRST.

3. Renal Failure

The older term:

Renal failure

is now usually replaced by more specific terminology such as:

Acute kidney injury – AKI

or

Chronic kidney disease – CKD.

In both situations, impaired filtration reduces creatinine clearance and causes:

Serum creatinine to rise.

4. Creatinine in Acute Kidney Injury

In AKI, creatinine does not always rise immediately after GFR falls.

There can be a delay before the blood level reaches a new steady state.

Therefore in rapidly evolving AKI:

Serum creatinine may underestimate the immediate severity of renal dysfunction.

This is why urine output and serial measurements are also important.

5. Large Muscle Bulk

The original notes correctly include:

Large muscle bulk.

People with greater skeletal muscle mass produce more creatinine.

Therefore a muscular person may have:

A relatively high baseline serum creatinine

despite normal renal function.

6. Rhabdomyolysis

Rhabdomyolysis causes extensive skeletal muscle breakdown.

This releases:

Myoglobin.

Potassium.

Phosphate.

Creatine and related metabolites.

Creatinine may rise because of:

Increased muscle breakdown

and, importantly,

AKI caused by pigment-associated tubular injury.

7. Rhabdomyolysis Pattern

Typical associated findings include:

Very high CK.

Dark urine.

Urine dipstick positive for blood with few or no RBCs.

Hyperkalaemia.

Hyperphosphataemia.

AKI.

Therefore:

RHABDOMYOLYSIS + RISING CREATININE → THINK BOTH MUSCLE BREAKDOWN AND RENAL INJURY.

8. Tubular Secretion of Creatinine

Although most creatinine is filtered by the glomerulus, a small amount is:

Secreted by proximal tubular cells.

Some drugs inhibit this secretion.

As a result:

Serum creatinine rises even though true GFR may remain unchanged.

9. Trimethoprim

The classic example is:

Trimethoprim.

Trimethoprim inhibits proximal tubular secretion of creatinine.

This can produce:

A modest increase in serum creatinine without a true reduction in GFR.

This is sometimes described as a:

Pseudo-rise in creatinine.

10. Cimetidine

Another classic drug that reduces tubular creatinine secretion is:

Cimetidine.

Therefore:

TRIMETHOPRIM OR CIMETIDINE → CREATININE MAY RISE WITHOUT TRUE RENAL DETERIORATION.

11. Potassium-Sparing Diuretics

The original notes state that:

Potassium-sparing diuretics

reduce tubular creatinine secretion.

This is too broad.

Some agents may influence creatinine handling, but not all potassium-sparing diuretics raise creatinine through the same mechanism.

A better high-yield association is:

Trimethoprim and cimetidine → inhibit tubular creatinine secretion.

Potassium-sparing drugs may also increase creatinine because of:

Haemodynamic effects

or underlying renal impairment.

12. Reduced Creatinine

A low serum creatinine usually reflects:

Reduced creatinine production

or

Increased renal clearance.

The most common cause is:

Low muscle mass.

13. Small Muscle Mass

Low muscle mass reduces creatinine production.

This occurs in:

Frailty.

Malnutrition.

Cachexia.

Muscle wasting disorders.

Amputation.

Advanced age.

Therefore:

A normal or low creatinine does not always mean normal kidney function.

14. Clinical Importance of Low Muscle Mass

A patient with severe muscle wasting may have:

Significant kidney dysfunction

while serum creatinine remains only mildly elevated or even apparently normal.

This is an important limitation of creatinine-based assessment.

15. Pregnancy and Low Creatinine

The original notes correctly include:

Pregnancy.

During pregnancy:

Renal plasma flow increases

and

GFR increases.

This increases creatinine clearance and lowers:

Serum creatinine.

16. Clinical Importance in Pregnancy

Because normal creatinine is lower during pregnancy, a value that would look normal in a non-pregnant adult may represent:

Abnormal renal function in pregnancy.

Therefore changes in creatinine during pregnancy should be interpreted carefully.

17. SIADH and Creatinine

The original notes include:

SIADH

as a cause of low creatinine.

This is not a strong or classic association.

SIADH mainly causes:

Water retention and dilutional hyponatraemia.

Serum urea and uric acid are more characteristically reduced.

Creatinine may occasionally be mildly diluted, but:

LOW CREATININE IS NOT A KEY DIAGNOSTIC FEATURE OF SIADH.

18. Urea

Urea is produced in the:

Liver.

It is formed through the urea cycle from nitrogen generated during:

Protein metabolism.

It is then excreted mainly through the:

Kidneys.

19. Urea Is Less Specific Than Creatinine

Serum urea is affected by many factors other than renal filtration.

These include:

Hydration.

Protein intake.

GI bleeding.

Catabolism.

Liver function.

Pregnancy.

For this reason:

UREA IS LESS SPECIFIC FOR GFR THAN CREATININE.

20. Raised Urea – Reduced GFR

Reduced renal filtration causes:

Reduced urea excretion.

Therefore urea rises in:

AKI.

CKD.

However, an elevated urea does not automatically mean intrinsic kidney disease because many non-renal factors can also raise it.

21. Dehydration

The original notes correctly include:

Dehydration.

In volume depletion, renal blood flow decreases and the kidney increases:

Sodium and water reabsorption.

Urea is also reabsorbed more extensively.

As a result:

Urea may rise disproportionately compared with creatinine.

22. Pre-Renal AKI

In a classic pre-renal state:

Urea reabsorption increases.

Creatinine is not reabsorbed to the same degree.

Therefore the:

Urea-to-creatinine ratio

may increase.

This pattern can support a diagnosis of:

Pre-renal hypoperfusion.

However, it is not perfectly specific.

23. Diuretics

The original notes include:

Diuretics.

Diuretics generally raise urea indirectly rather than directly.

Excessive diuresis can cause:

Volume depletion.

This produces:

Pre-renal hypoperfusion

and therefore:

Raised urea ± raised creatinine.

24. Gastrointestinal Bleeding

The original notes correctly include:

GI bleeding.

This is particularly important in:

Upper GI bleeding.

Blood in the gastrointestinal tract is digested as a:

Protein load.

The absorbed amino acids are then metabolised by the liver, increasing:

Urea production.

25. Urea in Upper GI Bleeding

Therefore:

UPPER GI BLEED → DIGESTED BLOOD → INCREASED PROTEIN LOAD → ↑ UREA.

A disproportionately high urea relative to creatinine may therefore suggest:

Upper GI bleeding, especially in the right clinical context.

26. Corticosteroids

Corticosteroids increase:

Protein catabolism.

This releases more amino acids for hepatic metabolism, increasing:

Urea production.

Therefore corticosteroids can cause:

Raised serum urea.

27. Tetracyclines

Some older tetracyclines have an:

Anti-anabolic effect

and can increase protein breakdown.

This may raise:

Serum urea.

However, this is an older association and is less emphasised in modern clinical practice.

28. High-Protein Diet

A high-protein diet increases:

Nitrogen intake.

More nitrogen is converted into:

Urea.

Therefore serum urea may rise even if renal function is normal.

29. Increased Catabolism

Any state with increased protein breakdown may raise urea.

Examples include:

Sepsis.

Major trauma.

Burns.

Severe infection.

Postoperative states.

Other hypercatabolic illnesses.

30. Reduced Urea

Low serum urea usually reflects:

Reduced urea production

or

Increased clearance/dilution.

Important causes include:

Severe liver disease.

Low protein intake.

SIADH.

Pregnancy.

31. Chronic Liver Disease

The original notes correctly include:

Chronic liver disease.

The liver is responsible for converting ammonia into:

Urea.

When hepatic function is severely impaired:

Urea synthesis falls.

Therefore serum urea may be low.

32. Severe Liver Failure

A useful pattern is:

Severe liver dysfunction → reduced urea synthesis → low serum urea.

At the same time, ammonia may rise because hepatic detoxification is impaired.

33. Starvation

Starvation reduces:

Protein intake.

This decreases the amount of nitrogen available for:

Urea production.

Therefore serum urea may be low.

34. Anabolic State

During an anabolic state, amino acids are preferentially used for:

Protein synthesis

rather than being broken down.

Therefore less nitrogen is converted into urea.

This may result in:

Reduced serum urea.

35. Alcohol Abuse

The original notes include:

Alcohol abuse.

Alcohol itself does not necessarily directly lower urea.

Low urea in chronic alcohol misuse more often reflects:

Poor nutrition.

Low protein intake.

Chronic liver disease.

Therefore the relationship is usually indirect.

36. SIADH and Low Urea

The original notes correctly include:

SIADH.

SIADH causes:

Excess water retention.

This leads to:

Dilutional hyponatraemia.

Serum urea is often reduced because of:

Dilution and altered renal handling of urea.

37. Typical SIADH Pattern

Typical laboratory features include:

Low serum sodium.

Low serum osmolality.

Inappropriately concentrated urine.

Urine sodium that is not suppressed.

Low serum uric acid.

Often low serum urea.

Therefore:

LOW UREA IS A SUPPORTIVE FEATURE OF SIADH.

38. Pregnancy and Low Urea

Pregnancy lowers urea because:

GFR increases.

This increases renal urea clearance.

In addition, nitrogen is increasingly used for:

Maternal and fetal tissue growth.

Therefore both urea and creatinine are commonly lower in normal pregnancy.

39. Urea and Creatinine in Pre-Renal AKI

In pre-renal AKI:

Urea often rises more than creatinine.

This occurs because:

Urea is reabsorbed with water

while creatinine is not significantly reabsorbed.

Therefore:

DISPROPORTIONATELY HIGH UREA → CONSIDER PRE-RENAL HYPOPERFUSION.

40. Urea and Creatinine in Acute Tubular Injury

In acute tubular injury:

Tubular function is impaired.

Urea reabsorption becomes less effective.

Therefore the disproportionate rise in urea seen in classic pre-renal states may be less marked.

However, these patterns overlap and should not be used alone to make the diagnosis.

41. Creatinine and eGFR

Serum creatinine is used in equations to estimate:

Glomerular filtration rate – eGFR.

The reliability of creatinine-based eGFR depends partly on normal relationships between:

Muscle mass and creatinine production.

42. When eGFR May Be Misleading

Creatinine-based eGFR may be less accurate in people with:

Very high muscle mass.

Very low muscle mass.

Severe malnutrition.

Amputation.

Rapidly changing renal function.

43. eGFR in Acute Kidney Injury

A particularly important point is:

eGFR is unreliable during rapidly changing AKI.

This is because serum creatinine is not in a:

Steady state.

Therefore AKI should be assessed using:

Serial creatinine measurements + urine output + clinical context.

44. Raised Creatinine – Note Form

Reduced GFR:

AKI.

CKD.

Pre-renal hypoperfusion.

Intrinsic renal disease.

Post-renal obstruction.

Large muscle bulk:

Higher baseline creatinine production.

Rhabdomyolysis:

Muscle breakdown plus possible pigment-induced AKI.

Reduced tubular creatinine secretion:

Trimethoprim.

Cimetidine.

May increase serum creatinine without true reduction in GFR.

45. Reduced Creatinine – Note Form

Small muscle mass:

Frailty.

Malnutrition.

Cachexia.

Muscle wasting.

Pregnancy:

Increased GFR and creatinine clearance.

SIADH:

May cause mild dilution, but low creatinine is not a characteristic diagnostic feature.

46. Raised Urea – Note Form

Reduced GFR:

AKI.

CKD.

Dehydration:

Reduced renal perfusion + increased urea reabsorption.

Diuretics:

May cause volume depletion and pre-renal azotaemia.

GI bleeding:

Digested blood acts as a protein load.

Especially characteristic of upper GI bleeding.

Corticosteroids:

Increase protein catabolism.

Tetracyclines:

Some older agents increase catabolism; less important in modern practice.

High-protein diet:

Increased nitrogen load.

Increased catabolism:

Sepsis.

Burns.

Trauma.

Severe illness.

47. Reduced Urea – Note Form

Chronic/severe liver disease:

Reduced hepatic urea production.

Starvation:

Reduced protein intake.

Anabolic state:

Reduced protein breakdown.

Alcohol misuse:

Usually through malnutrition or chronic liver disease.

SIADH:

Dilution and increased renal urea handling.

Pregnancy:

Increased GFR and increased nitrogen utilisation.

48. Important Corrections to the Original Notes

The term:

“Renal failure”

is better replaced with:

AKI or CKD, depending on the situation.

The statement:

“Potassium-sparing diuretics reduce tubular creatinine secretion”

is too broad.

The classic high-yield drug association is:

TRIMETHOPRIM OR CIMETIDINE → REDUCED TUBULAR CREATININE SECRETION → MODEST CREATININE RISE WITHOUT TRUE GFR FALL.

SIADH is much more strongly associated with:

LOW UREA

than with low creatinine.

Diuretics usually raise urea indirectly because they can cause:

VOLUME DEPLETION AND PRE-RENAL HYPOPERFUSION.

Alcohol misuse generally lowers urea indirectly through:

MALNUTRITION, LOW PROTEIN INTAKE OR LIVER DISEASE.

Key Clinical Pattern

Remember:

↑ CREATININE → THINK REDUCED GFR FIRST.

Also consider:

LARGE MUSCLE MASS + RHABDOMYOLYSIS + TRIMETHOPRIM/CIMETIDINE.

↓ CREATININE → THINK LOW MUSCLE MASS OR PREGNANCY.

↑ UREA → THINK REDUCED GFR + DEHYDRATION + UPPER GI BLEED + HIGH PROTEIN + CATABOLISM.

↓ UREA → THINK LIVER DISEASE + LOW PROTEIN INTAKE + SIADH + PREGNANCY.

And the most useful overall distinction is:

CREATININE = MORE INFLUENCED BY GFR AND MUSCLE MASS.

UREA = MORE INFLUENCED BY GFR, HYDRATION, PROTEIN METABOLISM AND LIVER FUNCTION.

Medicine – Urine Microscopy

Urine microscopy is a useful investigation for identifying abnormalities within the kidneys and urinary tract. Examination of urinary sediment can reveal white blood cells, bacteria, red blood cells, epithelial cells and different types of casts. The pattern of these findings can help distinguish urinary infection, glomerular inflammation, tubular injury and chronic kidney disease.

An important principle is that free cells may originate anywhere along the urinary tract, whereas casts are formed within renal tubules and collecting ducts. Therefore, cellular casts usually indicate pathology arising within the kidney itself.

1. White Blood Cells

An increased number of white blood cells in the urine is known as:

Pyuria.

Pyuria indicates inflammation somewhere within the urinary system, although it does not necessarily mean that a bacterial UTI is present.

Urinary Tract Infection

The most common cause of pyuria is:

Urinary tract infection – UTI.

In a typical bacterial UTI, urine microscopy may demonstrate:

White cells + bacteria.

The patient may also experience dysuria, urinary frequency, urgency and suprapubic discomfort.

Urethral or Vaginal Infection

White cells can enter a urine specimen from:

Urethritis

or

Vaginal inflammation/infection.

They may therefore be present even when there is no infection within the bladder or kidneys.

Contamination is more likely when the urine contains many:

Squamous epithelial cells.

Renal Tract Calculi

Renal or ureteric stones may cause:

Pyuria + haematuria.

The stone irritates the urinary epithelium and produces local inflammation.

If white cells are present but routine bacterial cultures are negative, the patient has:

Sterile pyuria.

Glomerulonephritis

White cells can occur in:

Glomerulonephritis – GN.

However, they are not the most characteristic microscopic finding.

GN is more strongly suggested by:

Dysmorphic RBCs + RBC casts + proteinuria.

Therefore, white cells may accompany glomerular inflammation, but RBC casts are much more diagnostically useful for GN.

Genitourinary Tuberculosis

Tuberculosis involving the urinary tract is a classic cause of:

Persistent sterile pyuria.

This means:

White cells are present in urine, but routine bacterial culture is negative.

Therefore:

Persistent sterile pyuria + appropriate TB risk → consider genitourinary TB.

2. Bacteria

The presence of bacteria in urine is called:

Bacteriuria.

Bacteriuria may represent:

True UTI, asymptomatic bacteriuria, or contamination.

The clinical context is therefore essential.

Bacteria in UTI

A symptomatic bacterial UTI commonly produces:

Bacteriuria + pyuria.

Other supportive findings may include positive:

Leukocyte esterase

and, with nitrate-reducing organisms:

Nitrites.

Asymptomatic Bacteriuria

Asymptomatic bacteriuria means significant bacteriuria in a person who does not have symptoms attributable to UTI.

The original statement:

“Asymptomatic bacteriuria without pyuria”

is too restrictive.

Asymptomatic bacteriuria can occur:

With or without pyuria.

The important feature is:

BACTERIURIA WITHOUT UTI SYMPTOMS.

Contamination

Bacteria seen on microscopy may result from contamination during collection rather than true infection.

Clues include:

Many squamous epithelial cells.

Mixed organisms on culture.

Lack of compatible urinary symptoms.

A properly collected:

Midstream clean-catch urine specimen

helps reduce this problem.

3. Red Blood Cells

Red blood cells in urine indicate:

Haematuria.

Haematuria may originate from the glomeruli or from elsewhere in the urinary tract.

Glomerular Haematuria

Glomerular bleeding is suggested by:

Dysmorphic RBCs.

Acanthocytes.

RBC casts.

Associated proteinuria.

This pattern strongly suggests:

Glomerulonephritis or another glomerular disorder.

Non-Glomerular Haematuria

Non-glomerular causes include:

Renal or ureteric calculi.

UTI.

Urinary tract malignancy.

Trauma.

Prostatic disease.

The RBCs are more likely to be relatively:

Uniform in appearance.

4. Urinary Casts

Urinary casts are cylindrical structures formed primarily in the:

Distal nephron and collecting ducts.

Their matrix consists mainly of:

Uromodulin, historically called Tamm–Horsfall protein.

Different materials can become incorporated into this protein matrix, producing different types of casts.

This makes casts particularly useful for identifying:

Intrinsic renal disease.

5. Hyaline Casts

Hyaline casts consist predominantly of uromodulin and contain few or no cells.

Unlike most cellular casts, a small number of hyaline casts can occur in:

Healthy individuals.

Concentrated Urine

Hyaline casts are more likely to form when urine is:

Concentrated.

This can occur with:

Dehydration or reduced urine flow.

Therefore their presence does not automatically indicate renal disease.

Exercise

Hyaline casts can appear temporarily following:

Strenuous exercise.

This can be a physiological finding.

Therefore:

EXERCISE + A FEW HYALINE CASTS ≠ NECESSARILY KIDNEY DISEASE.

Febrile Illness

Hyaline casts may also appear during:

Febrile illness.

Again, this is relatively nonspecific.

The important distinction is that isolated hyaline casts are much less concerning than cellular or muddy brown casts.

6. Granular Casts

Granular casts contain:

Degenerated cellular material and proteins.

They may range from fine granular casts to coarse, dense granular casts.

Numerous coarse granular casts are more likely to indicate:

Renal pathology.

Muddy Brown Granular Casts

The most clinically important granular casts are:

Muddy brown granular casts.

These are strongly associated with:

Acute tubular injury – ATI, traditionally called acute tubular necrosis – ATN.

Tubular epithelial cells become injured, detach and degenerate within the tubular lumen, producing the characteristic granular appearance.

Therefore:

AKI + MUDDY BROWN GRANULAR CASTS → THINK ACUTE TUBULAR INJURY.

Granular Casts in Chronic Glomerular Disease

The original notes associate granular casts with:

Chronic proliferative GN

and

Membranous GN.

Granular casts can occur in chronic renal parenchymal disease, but they are relatively nonspecific.

For active GN, the more characteristic finding is:

Red-cell casts.

Membranous Nephropathy

Membranous nephropathy usually presents with:

Heavy proteinuria and nephrotic syndrome.

Because nephrotic syndrome produces lipiduria, urine may contain:

Oval fat bodies and fatty casts.

These findings are more characteristic than granular casts.

Diabetic Kidney Disease

Granular casts can also occur in advanced:

Diabetic kidney disease.

However, the characteristic urinary abnormality in diabetic kidney disease is:

Persistent albuminuria/proteinuria.

Granular casts are therefore not specific for diabetes.

7. Red Cell Casts

Red blood cell casts are among the most important findings on urine microscopy.

They form when RBCs enter renal tubules and become incorporated into the cast matrix.

This means the bleeding originates from:

Renal parenchyma, particularly the glomeruli.

Glomerular Bleeding

A free RBC in urine could originate from:

Kidney, ureter, bladder, prostate or urethra.

An RBC cast, however, must have formed within:

The kidney.

Therefore:

RBC CAST → GLOMERULAR BLEEDING UNTIL PROVEN OTHERWISE.

Glomerulonephritis

The classic cause of RBC casts is:

Glomerulonephritis.

Examples include:

IgA nephropathy.

Post-infectious GN.

Lupus nephritis.

ANCA-associated GN.

Anti-GBM disease.

Nephritic Sediment

A classic active nephritic urine sediment contains:

Dysmorphic RBCs + RBC casts + proteinuria.

This strongly indicates:

Inflammatory glomerular disease.

8. White Cell Casts

White blood cell casts form when leukocytes become trapped within the tubular protein matrix.

Because they form within renal tubules, they indicate:

Inflammation within the kidney rather than simply the lower urinary tract.

Pyelonephritis

The classic association is:

Acute pyelonephritis.

Typical findings may include:

Fever.

Flank pain.

Pyuria.

Bacteriuria.

WBC casts.

The presence of WBC casts helps distinguish an upper urinary tract infection from uncomplicated cystitis.

Acute Interstitial Nephritis

An important additional cause is:

Acute interstitial nephritis – AIN.

AIN may produce:

Sterile pyuria.

WBC casts.

Microscopic haematuria.

Mild-to-moderate proteinuria.

AKI.

Therefore:

WBC CASTS → THINK PYELONEPHRITIS OR AIN.

9. Epithelial Cell Casts

Renal tubular epithelial cells may detach from damaged tubules and become incorporated into casts.

These are called:

Renal tubular epithelial cell casts.

Their presence indicates:

Tubular epithelial injury.

Acute Tubular Injury

The strongest association is:

Acute tubular injury / ATN.

The urine may contain:

Renal tubular epithelial cells.

Epithelial cell casts.

Muddy brown granular casts.

This combination is highly supportive of:

Acute tubular injury.

Acute Glomerulonephritis

The original notes also associate epithelial cell casts with:

Acute GN.

They can occur when severe glomerular disease causes secondary tubular injury.

However, the classic urinary cast of acute GN remains:

RED-CELL CASTS.

10. Fatty Casts

An important additional type is:

Fatty casts.

These contain lipid droplets and are associated with:

Heavy proteinuria and nephrotic syndrome.

The urine may also contain lipid-filled tubular cells called:

Oval fat bodies.

Maltese Cross Appearance

When examined under polarised light, lipid-containing structures may demonstrate:

Maltese-cross birefringence.

Therefore:

FATTY CASTS + OVAL FAT BODIES → THINK NEPHROTIC SYNDROME.

11. Waxy Casts

Waxy casts are associated with prolonged tubular stasis and advanced renal parenchymal disease.

They are particularly associated with:

Advanced chronic kidney disease.

Their presence generally suggests more severe and chronic renal impairment than isolated hyaline casts.

12. Broad Casts

Broad casts are unusually wide casts that form in dilated collecting ducts.

They are classically associated with:

Advanced CKD.

The older term:

“Renal failure casts”

has sometimes been used for broad waxy casts.

13. Urine Microscopy in Pre-Renal AKI

In uncomplicated pre-renal AKI, the renal tubules remain structurally intact.

Therefore urine sediment is usually:

Bland.

There may be:

Hyaline casts.

This contrasts with acute tubular injury, where the sediment becomes much more active.

14. Urine Microscopy in Acute Tubular Injury

Acute tubular injury typically produces:

Muddy brown granular casts.

Renal tubular epithelial cells.

Epithelial cell casts.

Therefore:

MUDDY BROWN CASTS = HIGH-YIELD CLUE TO ATI/ATN.

15. Urine Microscopy in Glomerulonephritis

GN typically produces an:

Active urinary sediment.

Characteristic findings include:

Dysmorphic RBCs.

Acanthocytes.

RBC casts.

Proteinuria.

Therefore:

RBC CASTS = HIGH-YIELD CLUE TO GN.

16. Urine Microscopy in Pyelonephritis

Pyelonephritis commonly produces:

Pyuria.

Bacteriuria.

WBC casts.

The presence of a WBC cast is important because it localises the inflammatory process to the:

Kidney.

17. Urine Microscopy in Acute Interstitial Nephritis

AIN may produce:

Sterile pyuria.

WBC casts.

Microscopic haematuria.

Mild proteinuria.

A useful clinical combination is:

NEW DRUG + AKI + STERILE PYURIA ± WBC CASTS → THINK AIN.

18. Urine Microscopy in Nephrotic Syndrome

Nephrotic syndrome can produce:

Heavy proteinuria.

Lipiduria.

Oval fat bodies.

Fatty casts.

Therefore:

FATTY CASTS → THINK NEPHROTIC SYNDROME.

19. White Cells – Note Form

UTI: Pyuria + bacteriuria.

Urethral/vaginal infection: White cells may contaminate urine.

Renal calculi: Pyuria ± haematuria; may be sterile.

GN: WBCs can occur, but RBC casts are more characteristic.

Genitourinary TB: Persistent sterile pyuria.

AIN: Sterile pyuria + WBC casts.

20. Bacteria – Note Form

UTI: Bacteriuria usually accompanied by urinary symptoms and often pyuria.

Asymptomatic bacteriuria: Bacteria without UTI symptoms; pyuria may be present or absent.

Contamination: Bacteria with many squamous epithelial cells or mixed organisms.

21. Urinary Casts – Note Form

Hyaline casts: May be normal; concentrated urine, dehydration, exercise or fever.

Muddy brown granular casts: Acute tubular injury / ATN.

Red-cell casts: Glomerular bleeding, especially GN.

White-cell casts: Pyelonephritis or acute interstitial nephritis.

Epithelial cell casts: Acute tubular injury.

Fatty casts: Nephrotic syndrome.

Waxy/broad casts: Advanced chronic kidney disease.

22. Important Corrections to the Original Notes

“Asymptomatic bacteriuria without pyuria” is too absolute. Asymptomatic bacteriuria can occur with or without pyuria; absence of urinary symptoms is the defining feature.

Granular casts can occur in chronic renal disease, but the classic high-yield association is:

MUDDY BROWN GRANULAR CASTS → ACUTE TUBULAR INJURY.

Although the original notes mention membranous GN with granular casts, membranous nephropathy is more characteristically associated with:

NEPHROTIC PROTEINURIA + LIPIDURIA ± FATTY CASTS.

RBC casts are strongly associated with:

GLOMERULONEPHRITIS.

WBC casts are not limited to pyelonephritis. They also occur in:

ACUTE INTERSTITIAL NEPHRITIS.

Epithelial cell casts most strongly indicate:

TUBULAR EPITHELIAL INJURY, especially ATI/ATN.

Key Clinical Pattern

The highest-yield associations are:

HYALINE CASTS → MAY BE NORMAL / DEHYDRATION / EXERCISE / FEVER.

MUDDY BROWN GRANULAR CASTS → ACUTE TUBULAR INJURY / ATN.

RBC CASTS → GLOMERULONEPHRITIS.

WBC CASTS → PYELONEPHRITIS OR AIN.

EPITHELIAL CELL CASTS → TUBULAR INJURY.

FATTY CASTS → NEPHROTIC SYNDROME.

WAXY/BROAD CASTS → ADVANCED CKD.

The easiest overall rule to remember is:

RBC CAST = GLOMERULUS.

WBC CAST = INTERSTITIUM OR PYELONEPHRITIS.

MUDDY BROWN/EPITHELIAL CAST = TUBULE.

FATTY CAST = NEPHROTIC PROTEIN LOSS.

Ophthalmology – Optic Disc Coloboma

Basics

Description

Optic disc coloboma is a congenital excavation of the optic nerve head caused by abnormal closure of the embryonic fissure.

The classic appearance is:

• Well-demarcated
• White or glistening
• Bowl-shaped excavation
• Usually involving the inferior portion of the optic disc

The defect may be confined to the optic nerve or extend into adjacent:

• Peripapillary retina
• Choroid
• Inferonasal fundus

Associated colobomas may involve the:

• Iris
• Ciliary body
• Choroid
• Retina

Embryology

Optic disc coloboma results from:

Incomplete closure of the proximal embryonic/optic fissure

Because the embryonic fissure lies inferonasally, colobomas characteristically affect the:

• Inferior
• Inferonasal

portion of the optic nerve and fundus.

Laterality

Optic disc coloboma may be:

• Unilateral
• Bilateral

Either pattern can occur.

Bilateral disease should increase suspicion for:

• Genetic syndromes
• Systemic malformations

Visual Acuity

Visual acuity varies widely.

It depends primarily on:

• Integrity of the papillomacular bundle
• Degree of macular involvement
• Associated retinal abnormalities
• Presence of amblyopia
• Development of retinal detachment

Visual acuity may range from:

• Near-normal
• Mildly reduced
• Profoundly impaired

The ophthalmoscopic appearance alone does not reliably predict visual acuity.

Risk Factors and Genetics

Optic disc coloboma may be:

• Sporadic
• Familial

Inheritance can be:

• Autosomal dominant
• Less commonly other patterns depending on syndrome

Important Genetic Associations

Genes and syndromes associated with optic nerve or ocular coloboma include:

• CHD7 – CHARGE syndrome
• PAX2 – renal coloboma syndrome / papillorenal syndrome
• Other developmental genes depending on phenotype

Genetic evaluation is especially appropriate in:

• Bilateral disease
• Family history
• Additional ocular abnormalities
• Systemic congenital anomalies

CHARGE Syndrome

CHARGE is classically associated with:

• Coloboma
• Heart defects
• Atresia of choanae
• Retardation of growth/development
• Genital abnormalities
• Ear abnormalities/hearing loss

It is commonly associated with pathogenic variants in:

CHD7

PAX2 / Renal Coloboma Syndrome

PAX2-related disease may produce:

• Optic nerve dysplasia or coloboma
• Renal hypoplasia
• Renal dysfunction
• Vesicoureteral abnormalities

Therefore, bilateral or atypical optic nerve coloboma may warrant consideration of:

• Renal history
• Blood pressure
• Urinalysis
• Renal function
• Renal imaging when clinically appropriate

Other Syndromic Associations

Optic nerve coloboma may occur with:

• Aicardi syndrome
• Walker-Warburg syndrome
• Goldenhar spectrum
• Focal dermal hypoplasia
• Linear nevus syndromes
• Other craniofacial or neurodevelopmental disorders

Associated Ocular Findings

Possible associated abnormalities include:

• Chorioretinal coloboma
• Iris coloboma
• Ciliary body coloboma
• Microphthalmia
• Strabismus
• Nystagmus
• Amblyopia
• Orbital cyst

Orbital Cyst

A congenital cyst may occasionally occur in association with:

• Optic nerve coloboma
• Microphthalmia
• Chorioretinal coloboma

It may communicate with the globe through the colobomatous defect.

Large cysts may cause:

• Orbital mass effect
• Proptosis
• Cosmetic asymmetry

Pathophysiology

The structural defect produces a congenital excavation at the junction between:

• Posterior globe
• Optic nerve

The excavation may contain:

• Dysplastic tissue
• Glial tissue
• Abnormal scleral architecture

These structural abnormalities may predispose to later retinal complications.

Diagnosis

Diagnosis is usually clinical based on characteristic optic disc morphology.

Important objectives are to determine:

• Visual function
• Extent of coloboma
• Macular involvement
• Presence of associated chorioretinal coloboma
• Presence of retinal detachment
• Associated systemic abnormalities

History

Ask about:

• Poor vision since childhood
• Strabismus
• Nystagmus
• Family history of coloboma
• Congenital abnormalities
• Developmental delay
• Hearing loss
• Cardiac abnormalities
• Renal disease
• Previous retinal detachment symptoms

Symptoms of Retinal Detachment

Patients and families should be educated about:

• Sudden increase in floaters
• Flashes of light
• Curtain or shadow in vision
• Sudden visual decline

These require urgent retinal examination.

Physical Examination

Perform a complete examination including:

• Visual acuity
• Cycloplegic refraction in children
• Pupils
• Ocular alignment
• Motility
• Anterior segment
• Dilated fundus examination

Optic Disc Appearance

Typical findings include:

• Enlarged optic nerve head
• Inferior excavation
• White or glistening base
• Sharply demarcated borders
• Relative preservation of the superior disc

More extensive disease may involve:

• Entire optic disc
• Adjacent inferior retina and choroid

Papillomacular Bundle

Visual prognosis is especially dependent on preservation of the:

Papillomacular bundle

If central axons are spared, useful central vision may remain despite a dramatic-appearing disc anomaly.

Chorioretinal Coloboma

When the defect extends into retina and choroid, typical findings include:

• Inferonasal white excavation
• Absent or thinned retina
• Exposed sclera
• Pigmented borders

These eyes have an important risk of:

Rhegmatogenous retinal detachment

from retinal breaks at or near the coloboma margin.

Retinal Detachment in Isolated Optic Disc Coloboma

Isolated optic disc coloboma may also develop:

Serous retinal detachment

particularly involving the macula.

Fluid may gain access through abnormal communications involving:

• Optic disc excavation
• Peripapillary retina

This mechanism differs from the typical rhegmatogenous detachment associated with large chorioretinal colobomas.

Amblyopia

Reduced vision in childhood may result from:

• Structural optic nerve abnormality
• Anisometropia
• Strabismus

Treatable amblyopia should not be overlooked simply because a congenital optic nerve anomaly is present.

Strabismus

Strabismus may occur because of:

• Asymmetric visual acuity
• Sensory deprivation

Management depends on:

• Visual potential
• Alignment
• Cosmetic and functional concerns

Diagnostic Testing

Optical Coherence Tomography

OCT is very useful for defining:

• Optic nerve excavation
• Peripapillary retinal structure
• Macular involvement
• Subretinal or intraretinal fluid
• Serous retinal detachment

Enhanced-depth imaging may further delineate deep disc architecture.

Fundus Photography

Baseline photography is useful for documenting:

• Disc appearance
• Extent of coloboma
• Associated retinal abnormalities
• Future change

Wide-Field Imaging

Wide-field imaging can help identify:

• Peripheral chorioretinal coloboma
• Retinal breaks
• Retinal detachment
• Pigmented borders

B-Scan Ultrasonography

B-scan may be useful when there is:

• Poor fundus view
• Suspected retinal detachment
• Orbital cyst
• Microphthalmia

Neuroimaging

MRI is not routinely required for every isolated typical optic disc coloboma.

Consider MRI when there are:

• Neurologic abnormalities
• Unusual disc appearance
• Suspected orbital cyst
• Brain malformations
• Syndromic features

Systemic Evaluation

A systemic examination is especially important in children.

Assess for:

• Craniofacial anomalies
• Ear abnormalities
• Hearing loss
• Cardiac disease
• Renal abnormalities
• Developmental delay
• Neurologic findings

Laboratory Testing

There is no routine laboratory test for isolated optic disc coloboma.

Testing should be directed toward suspected syndromic or systemic disease.

Differential Diagnosis

The major congenital excavated optic disc anomalies include:

• Morning glory disc anomaly
• Peripapillary staphyloma
• Optic disc pit
• Severe glaucomatous cupping in selected cases

Morning Glory Disc Anomaly

Morning glory disc typically demonstrates:

• Funnel-shaped excavation
• Enlarged dysplastic disc
• Central glial tuft
• Radially oriented retinal vessels
• Peripapillary pigmentary ring

It is often associated with:

• Moyamoya disease
• Carotid abnormalities
• Basal encephalocele
• Pituitary abnormalities

These systemic associations differ significantly from those of typical optic disc coloboma.

Optic Disc Coloboma vs Morning Glory

Optic Disc Coloboma

• Inferior excavation
• Embryonic fissure defect
• Superior disc often preserved
• May coexist with inferonasal chorioretinal coloboma

Morning Glory Disc

• Funnel-shaped whole-disc excavation
• Central glial tuft
• Radial vessels
• Pigmented peripapillary ring

Peripapillary Staphyloma

Peripapillary staphyloma consists of:

• Deep excavation surrounding the optic nerve

with a relatively:

Normal-appearing optic disc within the excavation

Unlike morning glory:

• No central glial tuft
• No characteristic radial vessels

Optic Disc Pit

Optic disc pits are usually:

• Smaller
• Gray-white depressions
• Often temporal
• Associated with serous macular detachment

They are generally much smaller than a true optic disc coloboma.

Treatment

There is no medical therapy that corrects the congenital structural defect.

Management focuses on:

• Maximizing visual potential
• Treating amblyopia
• Correcting refractive error
• Monitoring for retinal detachment
• Treating associated strabismus
• Managing retinal complications

Refractive Correction

Children should receive accurate cycloplegic refraction.

Correct:

• Hyperopia
• Myopia
• Astigmatism
• Anisometropia

to maximize visual development.

Amblyopia Therapy

If amblyopia is present and useful visual potential remains, treatment may include:

• Optical correction
• Patching
• Atropine penalization when appropriate

Structural disease does not automatically eliminate the potential benefit of amblyopia treatment.

Strabismus Surgery

Strabismus surgery may be considered for:

• Significant misalignment
• Abnormal head posture
• Cosmetic concerns
• Functional binocular goals where possible

Retinal Detachment Treatment

Retinal detachment requires retina specialist management.

Depending on mechanism, treatment may include:

• Vitrectomy
• Laser photocoagulation
• Scleral buckle
• Internal tamponade
• Combination surgery

Serous Macular Detachment

Serous detachment associated with the optic disc excavation can be challenging.

Treatment may involve:

• Vitrectomy
• Peripapillary laser in selected cases
• Gas tamponade
• Other individualized retinal surgical techniques

There is no single universally successful strategy.

Prophylactic Laser

Routine prophylactic laser around an asymptomatic optic disc coloboma is not universally recommended.

In associated chorioretinal coloboma, prophylactic laser to the coloboma margin has been considered in selected high-risk eyes, but evidence and practice vary.

Management should be individualized by a retina specialist.

Eye Protection

If one eye has significantly reduced vision, recommend:

Protective impact-resistant eyewear

to protect the better-seeing eye.

This is particularly important for children and monocular patients.

Low-Vision Rehabilitation

Patients with bilateral significant visual impairment may benefit from:

• Low-vision services
• Magnification
• Electronic visual aids
• Educational accommodations
• Orientation and mobility support

Genetic Counseling

Consider genetic counseling when:

• Bilateral disease is present
• A syndrome is suspected
• There is a family history
• Parents are planning future pregnancies

Molecular testing may be useful when a specific syndrome or gene is suspected.

Follow-Up

Regular ophthalmic follow-up should monitor:

• Visual acuity
• Refraction
• Amblyopia
• Strabismus
• Macula
• Peripheral retina
• Retinal detachment

Frequency depends on:

• Age
• Extent of coloboma
• Associated retinal findings
• Previous retinal complications

Prognosis

Visual prognosis is highly variable.

It depends primarily on:

• Papillomacular bundle involvement
• Macular involvement
• Associated chorioretinal disease
• Amblyopia
• Retinal detachment

Some eyes maintain good vision despite a striking disc anomaly.

Others have profound congenital visual impairment.

Retinal Detachment Risk

A major long-term concern is:

Acquired retinal detachment

This may occur years after the congenital anomaly is diagnosed.

Therefore, patients require long-term surveillance.

Complications

Important complications include:

• Retinal detachment
• Serous macular detachment
• Rhegmatogenous retinal detachment with associated chorioretinal coloboma
• Amblyopia
• Strabismus
• Progressive visual loss from retinal complications

Ophthalmology Pearls

• Optic disc coloboma is a congenital inferonasal/inferior excavation caused by incomplete closure of the embryonic fissure.
• The classic lesion is a white, bowl-shaped excavation involving the inferior optic disc.
• Visual acuity depends more on papillomacular bundle and macular involvement than on the dramatic appearance of the disc.
• Optic disc coloboma may be isolated or associated with iris, ciliary body, and chorioretinal colobomas.
• CHD7/CHARGE syndrome and PAX2-related renal coloboma syndrome are important genetic associations.
• Bilateral disease or systemic congenital abnormalities should prompt genetic and systemic evaluation.
• Amblyopia remains treatable and should not be overlooked because a structural optic nerve defect is present.
• The major long-term ocular complication is retinal detachment.
• Isolated optic disc coloboma may produce serous retinal detachment, whereas associated chorioretinal coloboma more commonly predisposes to rhegmatogenous detachment.
• Differentiate optic disc coloboma from morning glory disc anomaly, which has a central glial tuft, radial vessels, and important cerebrovascular associations.
• Peripapillary staphyloma contains a relatively normal disc within a deep peripapillary excavation.
• Regular lifelong retinal surveillance and protective eyewear for patients with asymmetric vision are important.

Ophthalmology – Open-Angle Glaucomas

Basics

Description

Open-angle glaucoma (OAG) refers to a group of chronic progressive optic neuropathies characterized by:

• Loss of retinal ganglion cells and their axons
• Characteristic optic nerve head cupping
• Retinal nerve fiber layer loss
• Corresponding visual field defects
• An anatomically open anterior chamber angle on gonioscopy

Intraocular pressure (IOP) is the most important modifiable risk factor, but glaucomatous damage can occur at either:

• Elevated IOP
• Statistically normal IOP

Classification

Open-angle glaucoma is broadly divided into:

Primary Open-Angle Glaucoma

Glaucomatous optic neuropathy with an open angle and no identifiable secondary ocular cause.

Includes:

• High-pressure primary open-angle glaucoma
• Normal-tension glaucoma

Secondary Open-Angle Glaucoma

Open-angle glaucoma caused by another ocular or systemic process.

Important examples include:

• Pseudoexfoliative glaucoma
• Pigmentary glaucoma
• Steroid-induced glaucoma
• Uveitic glaucoma
• Traumatic/angle-recession glaucoma
• Lens-related glaucoma
• Glaucoma following ocular surgery
• Elevated episcleral venous pressure
• Certain metabolic or infiltrative disorders

Ocular Hypertension

Ocular hypertension is different from glaucoma.

It consists of:

• Elevated IOP
• Open angles
• No glaucomatous optic nerve damage
• No corresponding visual field loss

It is a risk state for future glaucoma rather than established optic neuropathy.

Epidemiology

Glaucoma is one of the leading causes of irreversible blindness worldwide.

Primary open-angle glaucoma becomes increasingly common with:

• Increasing age
• Family history
• African ancestry
• Certain genetic backgrounds

A large proportion of affected individuals remain undiagnosed because early disease is usually asymptomatic.

Risk Factors

Important risk factors for developing or progressing open-angle glaucoma include:

• Elevated IOP
• Increasing age
• Family history of glaucoma
• African ancestry
• Thin central corneal thickness
• Myopia
• Large vertical cup-to-disc ratio
• Disc hemorrhage
• Lower ocular perfusion pressure
• Greater baseline structural or visual field damage

Possible systemic associations include:

• Migraine
• Vascular dysregulation
• Sleep apnea
• Systemic hypotension

These associations are particularly discussed in normal-tension glaucoma.

Genetics

Primary open-angle glaucoma is genetically heterogeneous.

Genes associated with selected forms include:

• MYOC
• OPTN
• TBK1
• Multiple polygenic risk loci

Most adult POAG is multifactorial rather than attributable to a single gene mutation.

Genetic testing is not routinely required in typical adult-onset disease.

Pathophysiology

The final common pathway is:

Retinal ganglion cell death → axonal loss → optic nerve cupping → visual field loss

Major mechanisms include:

• Mechanical stress at the lamina cribrosa
• Impaired axoplasmic transport
• Ischemia and vascular dysregulation
• Mitochondrial dysfunction
• Oxidative stress
• Neuroinflammation

Role of Intraocular Pressure

IOP is the most important treatable risk factor.

Damage may occur because of:

• Absolute pressure elevation
• Pressure fluctuations
• Individual susceptibility of the optic nerve

A “normal” IOP does not guarantee protection from glaucoma.

Conversely, some patients tolerate elevated IOP for years without developing damage.

Aqueous Humor Dynamics

IOP depends on the balance between:

• Aqueous humor production by the ciliary body
• Trabecular outflow
• Uveoscleral outflow
• Episcleral venous pressure

Most OAG therapies work by:

• Decreasing aqueous production
• Increasing trabecular outflow
• Increasing uveoscleral outflow

Diagnosis

Diagnosis requires integration of:

• IOP
• Gonioscopy
• Optic nerve appearance
• OCT
• Visual field testing
• Central corneal thickness
• Longitudinal change

The diagnosis should not be based on IOP alone.

History

Ask about:

• Family history of glaucoma
• Previous elevated IOP
• Steroid exposure
• Ocular trauma
• Uveitis
• Previous ocular surgery
• Migraine
• Sleep apnea
• Systemic hypotension
• Vascular disease
• Medication adherence
• Previous laser or glaucoma surgery

Symptoms

Early POAG is typically:

Asymptomatic

Central visual acuity usually remains good until advanced disease.

Late symptoms may include:

• Peripheral field loss
• Difficulty with contrast
• Trouble navigating in dim light
• Reading difficulty from paracentral loss
• Advanced tunnel vision

Visual Acuity

Visual acuity may remain normal until late disease.

Reduced central vision early in the course should raise concern for:

• Macular disease
• Optic neuropathy
• Advanced central glaucomatous damage
• Another diagnosis

Pupillary Examination

A relative afferent pupillary defect may occur when glaucoma is:

• Markedly asymmetric
• Advanced in one eye

Gonioscopy

Gonioscopy is mandatory in the evaluation of glaucoma.

Open-angle glaucoma requires visualization of the trabecular meshwork.

Gonioscopy also helps detect secondary causes such as:

• Pigment deposition
• Pseudoexfoliation
• Angle recession
• Neovascularization
• Peripheral anterior synechiae
• Inflammatory debris

Central Corneal Thickness

Pachymetry should be obtained because CCT influences:

• IOP interpretation
• Risk stratification

Thin corneas may underestimate IOP and are associated with greater glaucoma risk.

There is no universally accepted formula to “correct” IOP numerically for CCT.

Optic Nerve Examination

A dilated stereoscopic optic nerve examination should evaluate:

• Cup-to-disc ratio
• Vertical cupping
• Neuroretinal rim thickness
• Focal notching
• Inter-eye asymmetry
• Disc hemorrhage
• Pallor
• RNFL defects

Characteristic Glaucomatous Optic Nerve Findings

Typical findings include:

• Progressive cup enlargement
• Inferotemporal rim thinning
• Superotemporal rim thinning
• Vertical elongation of the cup
• Focal rim notch
• Laminar dot sign
• Acquired optic nerve pit
• Corresponding RNFL wedge defect

ISNT Rule

In many normal optic nerves, rim thickness follows approximately:

Inferior > Superior > Nasal > Temporal

Violation of this pattern can raise suspicion for glaucoma.

However, the ISNT rule is not sufficiently specific to diagnose glaucoma by itself.

Disc Hemorrhage

A splinter or flame-shaped hemorrhage at the disc margin is an important sign.

It is associated with:

• Higher risk of progression
• Localized RNFL loss
• Normal-tension glaucoma in particular

A new disc hemorrhage should prompt reassessment of:

• Target IOP
• Adherence
• Progression rate

Optic Disc Pallor

Glaucoma usually produces:

Cupping greater than pallor

If optic disc pallor is excessive relative to cupping, consider:

• Ischemic optic neuropathy
• Compressive optic neuropathy
• Toxic/nutritional optic neuropathy
• Hereditary optic neuropathy
• Prior optic neuritis

Optical Coherence Tomography

OCT is central to modern glaucoma diagnosis and follow-up.

It evaluates:

• Peripapillary RNFL
• Macular ganglion cell complex
• Ganglion cell–inner plexiform layer
• Optic nerve head

Structural Progression

Serial OCT can detect:

• Progressive RNFL thinning
• Ganglion cell loss
• Focal structural change

Structural progression may precede detectable visual field loss.

Preperimetric Glaucoma

Some patients have clear structural glaucomatous damage with:

• Normal standard automated perimetry

This is called:

Preperimetric glaucoma

Thus, a normal visual field does not exclude early glaucoma.

Visual Field Testing

Standard automated perimetry is used to detect functional damage.

Typical glaucomatous defects include:

• Paracentral scotoma
• Nasal step
• Arcuate scotoma
• Seidel scotoma
• Temporal wedge
• Advanced generalized constriction

Structure-Function Correlation

Glaucomatous field defects should correspond anatomically to optic nerve and RNFL damage.

For example:

• Superior RNFL loss → inferior visual field defect
• Inferior RNFL loss → superior visual field defect

Poor correlation should raise suspicion for another optic neuropathy.

Central Visual Field Testing

A 10-2 field is useful when there is:

• Paracentral damage
• Fixation-threatening disease
• Advanced glaucoma

A 24-2C strategy may also improve central sampling.

Optic Disc Photography

Baseline and serial optic disc photographs remain valuable because they can document:

• Progressive rim loss
• Disc hemorrhage
• Cup enlargement
• RNFL changes

They complement OCT rather than being replaced by it.

IOP Measurement

Goldmann applanation tonometry remains the clinical reference standard.

Important considerations include:

• Time of day
• CCT
• Corneal biomechanics
• Measurement technique
• IOP fluctuation

Repeated measurements may be useful in selected patients.

Diurnal IOP Variation

Some patients have clinically important pressure peaks outside routine office hours.

Consider repeated measurements when:

• Progression occurs despite apparently low office IOP
• IOP variability is suspected
• Normal-tension glaucoma is being evaluated

Differential Diagnosis

Open-angle glaucoma is a diagnosis of exclusion.

Important mimics include:

• Physiologic large cupping
• High myopia
• Congenital optic disc anomalies
• Optic nerve coloboma
• Tilted disc
• Optic nerve pits
• Dominant optic atrophy
• Ischemic optic neuropathy
• Compressive optic neuropathy
• Toxic/nutritional optic neuropathy
• Optic neuritis
• Prior papilledema

Neuroimaging Red Flags

Consider neuroimaging when there is:

• Pallor greater than cupping
• Marked visual acuity loss
• Central scotoma inconsistent with glaucoma
• Color vision loss out of proportion
• Rapid progression
• Severe unilateral disease
• Hemianopic visual field defect
• Neurologic symptoms

Treatment Principles

The established treatment goal is:

Lower IOP sufficiently to slow progression and preserve useful lifetime vision.

The target IOP is individualized according to:

• Baseline IOP
• Disease severity
• Rate of progression
• Age
• Life expectancy
• Central visual field involvement
• Fellow-eye status

Target IOP

There is no single safe IOP for every patient.

A commonly used initial framework is:

Mild glaucoma

Approximately 20–30% reduction from baseline

Moderate glaucoma

Often 30% or more

Advanced glaucoma

May require very low target pressures

Targets should be revised according to actual progression.

First-Line Treatment Options

Modern initial treatment commonly includes:

• Selective laser trabeculoplasty
• Prostaglandin analog
• Sometimes both

Choice depends on:

• Disease severity
• Patient preference
• Adherence
• Cost
• Ocular surface disease
• Expected treatment burden

Selective Laser Trabeculoplasty

SLT lowers IOP by improving trabecular outflow.

Advantages include:

• Effective IOP reduction
• No daily medication adherence
• Minimal systemic effects
• Can be repeated in selected patients

SLT is now widely accepted as:

A first-line treatment option for primary open-angle glaucoma and ocular hypertension

rather than merely an adjunct after medications fail.

Prostaglandin Analogs

Examples include:

• Latanoprost
• Travoprost
• Bimatoprost
• Tafluprost
• Latanoprostene bunod

They primarily increase uveoscleral and/or trabecular outflow.

Advantages:

• Strong IOP lowering
• Once-daily dosing
• Minimal systemic effects

Prostaglandin Adverse Effects

Possible adverse effects include:

• Conjunctival hyperemia
• Eyelash growth
• Periocular skin pigmentation
• Iris darkening
• Prostaglandin-associated periorbitopathy

Beta-Blockers

Examples:

• Timolol
• Betaxolol

They lower IOP by reducing aqueous production.

Use cautiously in:

• Asthma
• COPD
• Bradycardia
• Heart block
• Symptomatic hypotension

Alpha-2 Agonists

Example:

• Brimonidine

Mechanisms include:

• Reduced aqueous production
• Increased uveoscleral outflow

Adverse effects include:

• Follicular allergy
• Dry mouth
• Fatigue
• Somnolence

Topical Carbonic Anhydrase Inhibitors

Examples:

• Dorzolamide
• Brinzolamide

They reduce aqueous production.

Often used as:

• Adjunctive therapy
• Combination therapy

Rho Kinase Inhibitors

Examples include:

• Netarsudil

They primarily improve trabecular outflow and may also reduce episcleral venous pressure.

Adverse effects include:

• Conjunctival hyperemia
• Corneal verticillata
• Subconjunctival hemorrhage

Cholinergic Agents

Pilocarpine increases trabecular outflow by contracting the ciliary muscle.

It is used far less often in chronic OAG because of:

• Brow ache
• Miosis
• Induced myopia
• Reduced night vision
• Retinal detachment concern in susceptible patients

Oral Carbonic Anhydrase Inhibitors

Examples:

• Acetazolamide
• Methazolamide

These may be used temporarily when rapid IOP reduction is required.

They are generally unsuitable for routine long-term therapy because of systemic adverse effects.

Medication Adherence

Adherence is a major determinant of treatment success.

Barriers include:

• Cost
• Complex regimens
• Ocular surface irritation
• Forgetfulness
• Poor understanding
• Difficulty instilling drops

Simplifying therapy can improve adherence.

Laser Trabeculoplasty

SLT has largely replaced argon laser trabeculoplasty in routine practice because it:

• Uses lower energy
• Causes less thermal damage
• Can be repeated more readily

Cataract Surgery

Phacoemulsification alone may modestly reduce IOP in some patients with open-angle glaucoma.

It is not usually sufficient treatment for advanced disease.

Minimally Invasive Glaucoma Surgery

MIGS procedures are increasingly used for:

• Mild to moderate glaucoma
• Reducing medication burden
• Combination with cataract surgery

Examples include:

• Trabecular micro-bypass stents
• Goniotomy
• Trabeculotomy
• Canal-based procedures

Limitations of MIGS

MIGS generally provides:

• Modest to moderate IOP reduction
• Lower complication rates than trabeculectomy

However, many MIGS procedures cannot reliably achieve the very low pressures required for:

• Advanced glaucoma
• Rapid progression
• Severe fixation-threatening disease

Trabeculectomy

Trabeculectomy remains one of the most effective methods for achieving:

Very low IOP

It is especially useful for:

• Advanced glaucoma
• Rapid progression
• Failure of medical/laser therapy

Trabeculectomy Complications

Potential complications include:

• Hypotony
• Shallow anterior chamber
• Choroidal effusion
• Blebitis
• Endophthalmitis
• Cataract progression
• Bleb failure

Glaucoma Drainage Devices

Tube shunts include:

• Ahmed
• Baerveldt
• Other drainage implants

They are particularly useful when:

• Trabeculectomy has failed
• Conjunctival scarring is present
• Secondary glaucoma exists
• Prior ocular surgery complicates filtration surgery

Cyclophotocoagulation

Cyclodestructive procedures reduce aqueous production by treating the ciliary body.

Modern approaches include:

• Transscleral cyclophotocoagulation
• Micropulse cyclophotocoagulation
• Endoscopic cyclophotocoagulation

They are increasingly used beyond blind painful eyes, but patient selection remains important.

Major Evidence From Clinical Trials

Several major studies established that lowering IOP reduces glaucoma risk and progression.

OHTS

The Ocular Hypertension Treatment Study showed that treating ocular hypertension reduced conversion to POAG.

At about 5 years:

• Untreated: ~9.5% developed glaucoma
• Treated: ~4.4%

Collaborative Normal-Tension Glaucoma Study

Approximately:

30% IOP reduction

significantly reduced progression in normal-tension glaucoma.

Early Manifest Glaucoma Trial

The EMGT demonstrated that:

Each additional mmHg of IOP reduction lowers the risk of progression

and confirmed the importance of pressure reduction even in relatively early glaucoma.

LiGHT Trial

The LiGHT trial supported:

SLT as an effective first-line treatment

for many patients with newly diagnosed open-angle glaucoma or ocular hypertension.

Many patients were able to remain drop-free for substantial periods.

Neuroprotection

Glaucoma is a neurodegenerative disease, and many direct neuroprotective strategies have been studied.

However:

No medication has yet been definitively proven to provide clinically meaningful neuroprotection independent of IOP lowering.

IOP reduction remains the only established treatment proven to slow progression.

Follow-Up

Follow-up frequency depends on:

• Disease severity
• Target IOP
• Progression rate
• Treatment changes
• Adherence

Mild Stable Disease

May often be monitored every:

4–6 months

with periodic:

• OCT
• Visual field testing
• Disc examination

Moderate or Advanced Disease

Often requires closer follow-up:

Every 2–4 months

depending on stability.

After Treatment Changes

Patients should be reassessed after:

• Starting new medication
• SLT
• Incisional surgery
• Significant IOP change

to confirm:

• Efficacy
• Safety
• Adherence

Rate of Progression

The key question in long-term management is:

How fast is the patient losing retinal ganglion cells and visual field?

Management should be intensified when progression threatens useful lifetime vision.

Patient Education

Patients should understand that:

• Glaucoma is usually asymptomatic until late.
• Vision already lost cannot currently be restored.
• Treatment aims to prevent further damage.
• Adherence and follow-up are essential.
• “Normal” IOP does not necessarily mean glaucoma is controlled.

Prognosis

Prognosis depends on:

• Disease severity at diagnosis
• Age
• Life expectancy
• Baseline IOP
• Rate of progression
• Central field involvement
• Treatment adherence
• Ability to achieve target IOP

Early diagnosis and appropriate treatment greatly reduce the risk of severe visual loss.

Complications

Uncontrolled open-angle glaucoma can lead to:

• Progressive RNFL loss
• Progressive visual field loss
• Paracentral scotoma
• Severe peripheral field constriction
• Loss of fixation
• Permanent visual impairment
• Blindness

Treatment complications may include:

• Ocular surface disease
• Medication intolerance
• Laser-related IOP spikes
• Hypotony
• Infection
• Surgical failure

Ophthalmology Pearls

• Open-angle glaucoma = characteristic glaucomatous optic neuropathy with an open angle on gonioscopy.
• IOP is the most important modifiable risk factor, but glaucoma can occur at statistically normal pressures.
• Diagnosis is based on optic nerve/RNFL damage and corresponding functional loss, not IOP alone.
• Gonioscopy is essential to distinguish open-angle from angle-closure and secondary mechanisms.
• Typical optic nerve findings include vertical cupping, focal rim notching, RNFL loss, and disc hemorrhage.
• Disc pallor greater than cupping suggests a nonglaucomatous optic neuropathy.
• OCT may detect structural loss before standard visual fields become abnormal—preperimetric glaucoma.
• Glaucomatous visual field defects should anatomically correspond to RNFL and disc damage.
• SLT and prostaglandin analogs are both appropriate first-line treatments in many patients.
• MIGS is useful mainly for mild to moderate disease and medication reduction; it may not achieve sufficiently low IOP for advanced glaucoma.
• Trabeculectomy remains one of the most effective procedures when a very low target IOP is required.
• Major trials consistently show that lowering IOP reduces the risk of glaucoma development and progression.
• No independent neuroprotective therapy has yet replaced IOP lowering as the evidence-based foundation of glaucoma treatment.

Ophthalmology – Ocular Syphilis

Basics

Description

Ocular syphilis is ocular involvement by the spirochete Treponema pallidum.

Syphilis is a chronic systemic infection capable of affecting essentially any ocular structure and is known as the:

“Great masquerader”

because it can mimic many inflammatory, infectious, vascular, and neoplastic eye diseases.

Ocular involvement may occur during any stage of syphilis and may present as:

• Anterior uveitis
• Intermediate uveitis
• Posterior uveitis
• Panuveitis
• Retinitis
• Retinal vasculitis
• Chorioretinitis
• Optic neuropathy
• Interstitial keratitis

A key management principle is:

Ocular syphilis should be treated with a neurosyphilis regimen, even when cerebrospinal fluid findings are normal.

Etiology

The causative organism is:

Treponema pallidum

a motile spirochete.

Transmission

Acquired Syphilis

Transmission occurs primarily through direct contact with infectious lesions during:

• Vaginal intercourse
• Anal intercourse
• Oral sex

Congenital Syphilis

Transmission occurs:

Transplacentally from an infected mother to the fetus

Maternal screening and treatment during pregnancy are essential for prevention.

Epidemiology

Ocular syphilis accounts for a small but important proportion of uveitis.

Its frequency varies according to:

• Geographic region
• Syphilis prevalence
• HIV prevalence
• Population studied

Ocular disease may occur in both:

• HIV-negative patients
• People living with HIV

Risk Factors

Important risk factors include:

• Unprotected sexual exposure
• Multiple sexual partners
• Men who have sex with men
• HIV infection
• Other sexually transmitted infections
• Intravenous drug use
• Previous syphilis infection or inadequately treated infection

Systemic Stages of Acquired Syphilis

Primary Syphilis

Classically presents with:

Painless chancre

at the inoculation site.

Regional lymphadenopathy may occur.

Secondary Syphilis

May produce:

• Diffuse maculopapular rash
• Palmar and plantar lesions
• Generalized lymphadenopathy
• Fever
• Malaise
• Condylomata lata

Ocular manifestations are particularly important during secondary disease but can occur at any stage.

Latent Syphilis

Serologic evidence of infection without active clinical manifestations.

It is classified as:

• Early latent
• Late latent
• Unknown duration

Tertiary Syphilis

Potential manifestations include:

• Cardiovascular syphilis
• Gummatous disease
• Neurologic disease

Neurologic and ocular involvement can actually occur much earlier and should not be regarded as exclusively “tertiary.”

Congenital Syphilis

Early Manifestations

May include:

• Hepatosplenomegaly
• Mucocutaneous lesions
• Rhinitis
• Bone abnormalities
• Chorioretinitis

Late Manifestations

Classical findings include:

• Frontal bossing
• Saddle nose
• Saber shins
• Hutchinson teeth
• Sensorineural hearing loss
• Interstitial keratitis

The classic Hutchinson triad consists of:

• Interstitial keratitis
• Hutchinson teeth
• Sensorineural deafness

Pathophysiology

Ocular injury results from:

• Direct spirochetal infection
• Host inflammatory response
• Immune-mediated tissue injury
• Vascular inflammation

This can affect both the anterior and posterior segments.

Clinical Presentation

Patients may report:

• Blurred vision
• Floaters
• Photophobia
• Ocular pain
• Redness
• Scotoma
• Metamorphopsia
• Reduced color vision
• Sudden or progressive visual loss

Disease may be:

• Unilateral
• Bilateral
• Asymmetric

Important Clinical Principle

Syphilis can imitate almost any form of uveitis.

Therefore:

Syphilis testing should be considered in essentially all unexplained uveitis, particularly posterior or panuveitis.

Anterior Segment Manifestations

Possible findings include:

• Granulomatous anterior uveitis
• Non-granulomatous anterior uveitis
• Keratic precipitates
• Iris nodules
• Posterior synechiae
• Elevated IOP
• Scleritis
• Episcleritis

Interstitial Keratitis

Classically associated with congenital syphilis.

Features may include:

• Stromal corneal inflammation
• Corneal vascularization
• Photophobia
• Reduced vision

After inflammation resolves, residual:

Ghost vessels

may remain in the corneal stroma.

Vitreous Involvement

Syphilitic posterior disease commonly produces:

• Vitritis
• Haze
• Inflammatory cells

The amount of vitritis may vary considerably.

Posterior Segment Manifestations

Syphilis may produce:

• Retinitis
• Chorioretinitis
• Retinal vasculitis
• Retinal vascular occlusion
• Neuroretinitis
• Optic neuritis
• Optic disc edema
• Exudative retinal detachment
• Placoid chorioretinitis

Acute Syphilitic Posterior Placoid Chorioretinitis

A particularly characteristic manifestation is:

Acute syphilitic posterior placoid chorioretinitis (ASPPC)

Typical appearance:

• Large
• Yellow-gray
• Placoid lesion
• At or near the macula
• Often involving the outer retina and RPE

ASPPC should strongly raise suspicion for syphilis.

OCT Findings in ASPPC

OCT may show:

• Disruption of the ellipsoid zone
• Outer retinal abnormalities
• RPE irregularity
• Hyperreflective material at the RPE/photoreceptor interface
• Later restoration with successful treatment

Fluorescein Angiography

FA may demonstrate:

• Early hypofluorescence
• Late staining
• Retinal vascular leakage
• Optic disc leakage
• Vasculitis

Indocyanine Green Angiography

ICG may demonstrate areas of:

• Choroidal hypofluorescence
• Choriocapillaris involvement

in selected posterior cases.

Fundus Autofluorescence

May help demonstrate:

• RPE disturbance
• Extent of placoid lesions
• Evolution with treatment

Retinal Vasculitis

Syphilitic vasculitis may involve:

• Arteries
• Veins
• Both

It can lead to:

• Vascular occlusion
• Retinal ischemia
• Neovascular complications

Optic Nerve Manifestations

Possible manifestations include:

• Optic neuritis
• Optic perineuritis
• Neuroretinitis
• Papillitis
• Optic disc edema
• Optic atrophy

MRI may be useful when optic nerve or central neurologic involvement is suspected.

Pupillary Findings

The classic Argyll Robertson pupil:

• Accommodates to near
• Reacts poorly or not at all to light

It is historically associated with neurosyphilis but is uncommon in modern practice.

Cranial Neuropathies

Neurosyphilis may produce:

• Oculomotor nerve palsy
• Trochlear nerve palsy
• Abducens nerve palsy
• Other neurologic deficits

Diagnosis

Diagnosis combines:

• Compatible ocular findings
• Syphilis serology
• Exclusion of important mimics

No single ocular appearance confirms syphilis.

Serologic Testing

Testing generally includes both:

1. Nontreponemal test
2. Treponemal test

Nontreponemal Tests

Examples:

• RPR
• VDRL

These provide a quantitative titer and are useful for monitoring treatment response.

Nontreponemal Titers

A clinically meaningful change is generally:

Fourfold change in titer

For example:

• 1:32 → 1:8 = fourfold decline
• 1:8 → 1:32 = fourfold rise

Titers are therefore useful for:

• Monitoring therapy
• Detecting reinfection
• Detecting treatment failure

False-Positive Nontreponemal Tests

False-positive results may occur with:

• Autoimmune disease
• Pregnancy
• Infection
• Older age
• Other inflammatory states

Therefore, reactive nontreponemal testing requires confirmation with a treponemal assay.

Prozone Phenomenon

Very high antibody concentrations may rarely cause a falsely negative nontreponemal test.

If clinical suspicion is strong despite a negative RPR/VDRL, the laboratory can repeat testing using:

Serial dilution

to exclude a prozone effect.

Treponemal Tests

Examples include:

• TP-PA
• FTA-ABS
• Treponemal enzyme immunoassays
• Chemiluminescent immunoassays

These usually remain positive indefinitely after infection.

Therefore:

Treponemal tests should not be used to monitor treatment response.

Reverse-Sequence Screening

Many laboratories now begin with a:

Treponemal immunoassay

followed by quantitative RPR or VDRL.

Discordant results may require a second treponemal test such as TP-PA.

HIV Testing

All patients diagnosed with ocular syphilis should be offered:

HIV testing

because coinfection is important for:

• Overall management
• STI counseling
• Follow-up

Other STI screening should also be considered.

Lumbar Puncture

Older recommendations favored lumbar puncture in virtually all ocular syphilis.

Modern practice is more selective.

When CSF Examination Is Indicated

Lumbar puncture is particularly appropriate when there are:

• Cranial nerve abnormalities
• Meningeal symptoms
• Cognitive changes
• Motor or sensory deficits
• Other neurologic manifestations

CSF evaluation typically includes:

• Cell count
• Protein
• CSF-VDRL

Isolated Ocular Syphilis

If a patient has:

• Reactive syphilis serology
• Confirmed ocular abnormalities
• No neurologic findings

CSF examination is not required before treatment.

Most importantly:

Treatment should not be delayed for lumbar puncture.

CSF-VDRL

CSF-VDRL is:

• Highly specific
• Relatively insensitive

Therefore, a positive result strongly supports neurosyphilis, but a negative result does not completely exclude it.

Neuroimaging

MRI brain and/or orbits may be useful when there is:

• Optic neuropathy
• Cranial nerve palsy
• Focal neurologic deficit
• Concern for CNS disease

Differential Diagnosis

Because syphilis is a great masquerader, the differential is broad.

Consider:

• Sarcoidosis
• Tuberculosis
• Toxoplasmosis
• Acute retinal necrosis
• CMV retinitis
• Behçet disease
• VKH
• HLA-B27-associated uveitis
• Intermediate uveitis
• APMPPE
• Other white-dot syndromes
• Lyme disease
• Fungal endophthalmitis
• Toxocariasis
• Primary vitreoretinal lymphoma

Treatment

Critical Principle

All ocular syphilis should be treated using a neurosyphilis regimen.

Do not use standard single-dose benzathine penicillin treatment alone for active ocular syphilis.

First-Line Treatment

The preferred regimen is:

Aqueous crystalline penicillin G

Total:

18–24 million units/day IV

administered as:

• 3–4 million units IV every 4 hours

or

• Continuous infusion

for:

10–14 days

Alternative Penicillin Regimen

If reliable adherence can be ensured:

• Procaine penicillin G 2.4 million units IM once daily
• Plus probenecid 500 mg orally four times daily

for:

10–14 days

Additional Benzathine Penicillin

Because neurosyphilis regimens are shorter than those used for late latent syphilis, clinicians may consider:

Benzathine penicillin G 2.4 million units IM weekly for 1–3 weeks

after completion of neurosyphilis therapy in selected patients, particularly when the underlying stage would otherwise require a longer course.

Penicillin Allergy

For nonpregnant patients with penicillin allergy, an alternative that may be considered is:

Ceftriaxone 1–2 g IM or IV daily for 10–14 days

However, evidence is less extensive than for penicillin.

If there is concern about ceftriaxone safety or reliability of alternative therapy:

• Penicillin allergy testing
• Desensitization

should be considered.

Pregnancy

Pregnant patients with syphilis should receive:

Penicillin

because penicillin is the only proven treatment that reliably treats maternal infection and prevents fetal syphilis.

Patients with true penicillin allergy should undergo:

Desensitization followed by penicillin therapy

HIV Coinfection

People with HIV and ocular syphilis are treated with the:

Same neurosyphilis regimen

as patients without HIV.

HIV status does not justify using a less intensive regimen.

Adjunctive Corticosteroids

Corticosteroids may be used to control severe ocular inflammation.

Options include:

• Topical corticosteroids
• Systemic corticosteroids
• Selected periocular therapy

However:

Antibiotic therapy is the essential treatment.

Corticosteroids should not substitute for adequate antimicrobial therapy.

Evidence for Steroids

Systemic corticosteroids are frequently used in severe:

• Posterior uveitis
• Optic neuritis
• Marked inflammatory disease

but controlled evidence proving additional benefit is limited.

If used, they should generally be administered:

With or after initiation of appropriate antibiotic therapy

rather than as isolated immunosuppression.

Cycloplegics

For anterior uveitis, cycloplegics may be used to:

• Relieve ciliary spasm
• Reduce pain
• Prevent posterior synechiae

Examples include:

• Cyclopentolate
• Homatropine
• Atropine in severe inflammation

Intravitreal Therapy

Intravitreal antimicrobial treatment is not routinely necessary when appropriate systemic penicillin therapy is given.

It may be considered only in unusual severe circumstances under specialist care.

Jarisch-Herxheimer Reaction

A Jarisch-Herxheimer reaction may occur within approximately 24 hours after treatment begins.

Features include:

• Fever
• Chills
• Headache
• Myalgia
• Temporary worsening of syphilitic lesions

It results from the inflammatory response to rapid spirochetal killing.

Management is generally:

Supportive

It is not a penicillin allergy.

Ocular Jarisch-Herxheimer Reaction

Rarely, ocular inflammation may transiently worsen after therapy begins.

Close observation is appropriate in patients with severe posterior disease or optic nerve involvement.

Congenital Syphilis

Congenital syphilis treatment depends on:

• Infant age
• Maternal treatment
• Neonatal examination
• Serology
• CSF evaluation

A commonly used regimen for confirmed or highly probable neonatal congenital syphilis is:

Aqueous crystalline penicillin G 50,000 units/kg/dose IV

given:

• Every 12 hours during the first 7 days of life
• Then every 8 hours

for a total of:

10 days

Alternative neonatal regimens are determined by pediatric infectious-disease protocols.

Partner Management

Sex partners require:

• Evaluation
• Serologic testing
• Treatment when indicated

This is essential to prevent:

• Reinfection
• Continued transmission

Public Health Considerations

Syphilis is a reportable infection in many jurisdictions.

Management may involve:

• Public health notification
• Partner services
• STI counseling

Follow-Up

Ophthalmic Follow-Up

Serial examination should assess:

• Visual acuity
• Anterior chamber inflammation
• Vitritis
• Retinitis
• Vasculitis
• Macular involvement
• Optic nerve function

Serologic Follow-Up

Treatment response is monitored with:

Quantitative RPR or VDRL titers

Use the same type of test when possible because RPR and VDRL titers are not directly interchangeable.

Expected Response

A favorable response generally includes:

• Clinical improvement
• Falling nontreponemal titers

A fourfold decline is a commonly used marker of adequate serologic response, although the expected timing varies with syphilis stage.

Serofast State

Some successfully treated patients remain persistently reactive at a low titer.

This is called:

Serofast

and does not automatically indicate treatment failure.

Interpretation depends on:

• Initial stage
• Initial titer
• Clinical response
• Reinfection risk

Treatment Failure or Reinfection

Consider further evaluation when there is:

• Recurrent ocular inflammation
• New syphilitic symptoms
• Sustained fourfold rise in RPR/VDRL titer
• Inadequate expected serologic response
• New exposure

Repeat Lumbar Puncture

Routine repeat CSF examination is generally unnecessary when there is:

• Appropriate clinical improvement
• Appropriate serologic response

unless neurologic or ocular findings fail to improve or recur.

Referral

Management should involve:

• Ophthalmology/uveitis specialist
• Infectious disease or sexual health specialist when appropriate

Neurology consultation may be useful when there are:

• Cranial neuropathies
• Cognitive changes
• Other neurologic manifestations

Patient Education

Patients should understand:

• Syphilis is treatable.
• Ocular syphilis requires intensive systemic therapy.
• Sexual partners may also require testing and treatment.
• Reinfection is possible.
• Follow-up blood testing is essential.
• HIV and other STI testing should be performed.

Prognosis

Visual prognosis depends on:

• Severity at presentation
• Duration before treatment
• Macular involvement
• Optic nerve involvement
• Degree of retinal ischemia
• Promptness of therapy

Early diagnosis and appropriate treatment often produce substantial visual recovery.

Poor Prognostic Features

Potentially unfavorable findings include:

• Severe visual loss at presentation
• Optic neuropathy
• Macular involvement
• Extensive retinitis
• Retinal vascular occlusion
• Delayed treatment
• Permanent retinal or optic nerve atrophy

Complications

Possible ocular complications include:

• Corneal scarring
• Cataract
• Secondary glaucoma
• Posterior synechiae
• Cystoid macular edema
• Retinal vascular occlusion
• Retinal detachment
• Macular atrophy
• Optic atrophy
• Permanent visual loss

Ophthalmology Pearls

• Syphilis is the “great masquerader” and can mimic almost any form of uveitis.
• Ocular syphilis can occur during any stage of systemic infection.
• All ocular syphilis should be treated with a neurosyphilis regimen, regardless of CSF findings.
• The preferred treatment is IV aqueous crystalline penicillin G for 10–14 days.
• A single IM dose of benzathine penicillin appropriate for uncomplicated early syphilis is not adequate treatment for active ocular syphilis.
• Acute syphilitic posterior placoid chorioretinitis is a particularly characteristic posterior manifestation.
• Diagnosis requires both a treponemal test and a quantitative nontreponemal test.
• RPR/VDRL is used for treatment monitoring; treponemal tests generally remain reactive and should not be used to monitor response.
• CSF examination is important when neurologic abnormalities are present, but isolated confirmed ocular disease does not require lumbar puncture before treatment.
• All patients should be tested for HIV and considered for other STI screening.
• Corticosteroids may control inflammation, but adequate antimicrobial treatment is the essential therapy.
• A Jarisch-Herxheimer reaction may temporarily worsen systemic or ocular inflammation after treatment begins.
• Prompt diagnosis is critical because syphilitic ocular disease is often highly treatable before irreversible retinal or optic nerve damage occurs.

Ophthalmology – Ocular Syphilis

Basics

Description

Ocular syphilis is ocular involvement by the spirochete Treponema pallidum.

Syphilis is a chronic systemic infection capable of affecting essentially any ocular structure and is known as the:

“Great masquerader”

because it can mimic many inflammatory, infectious, vascular, and neoplastic eye diseases.

Ocular involvement may occur during any stage of syphilis and may present as:

• Anterior uveitis
• Intermediate uveitis
• Posterior uveitis
• Panuveitis
• Retinitis
• Retinal vasculitis
• Chorioretinitis
• Optic neuropathy
• Interstitial keratitis

A key management principle is:

Ocular syphilis should be treated with a neurosyphilis regimen, even when cerebrospinal fluid findings are normal.

Etiology

The causative organism is:

Treponema pallidum

a motile spirochete.

Transmission

Acquired Syphilis

Transmission occurs primarily through direct contact with infectious lesions during:

• Vaginal intercourse
• Anal intercourse
• Oral sex

Congenital Syphilis

Transmission occurs:

Transplacentally from an infected mother to the fetus

Maternal screening and treatment during pregnancy are essential for prevention.

Epidemiology

Ocular syphilis accounts for a small but important proportion of uveitis.

Its frequency varies according to:

• Geographic region
• Syphilis prevalence
• HIV prevalence
• Population studied

Ocular disease may occur in both:

• HIV-negative patients
• People living with HIV

Risk Factors

Important risk factors include:

• Unprotected sexual exposure
• Multiple sexual partners
• Men who have sex with men
• HIV infection
• Other sexually transmitted infections
• Intravenous drug use
• Previous syphilis infection or inadequately treated infection

Systemic Stages of Acquired Syphilis

Primary Syphilis

Classically presents with:

Painless chancre

at the inoculation site.

Regional lymphadenopathy may occur.

Secondary Syphilis

May produce:

• Diffuse maculopapular rash
• Palmar and plantar lesions
• Generalized lymphadenopathy
• Fever
• Malaise
• Condylomata lata

Ocular manifestations are particularly important during secondary disease but can occur at any stage.

Latent Syphilis

Serologic evidence of infection without active clinical manifestations.

It is classified as:

• Early latent
• Late latent
• Unknown duration

Tertiary Syphilis

Potential manifestations include:

• Cardiovascular syphilis
• Gummatous disease
• Neurologic disease

Neurologic and ocular involvement can actually occur much earlier and should not be regarded as exclusively “tertiary.”

Congenital Syphilis

Early Manifestations

May include:

• Hepatosplenomegaly
• Mucocutaneous lesions
• Rhinitis
• Bone abnormalities
• Chorioretinitis

Late Manifestations

Classical findings include:

• Frontal bossing
• Saddle nose
• Saber shins
• Hutchinson teeth
• Sensorineural hearing loss
• Interstitial keratitis

The classic Hutchinson triad consists of:

• Interstitial keratitis
• Hutchinson teeth
• Sensorineural deafness

Pathophysiology

Ocular injury results from:

• Direct spirochetal infection
• Host inflammatory response
• Immune-mediated tissue injury
• Vascular inflammation

This can affect both the anterior and posterior segments.

Clinical Presentation

Patients may report:

• Blurred vision
• Floaters
• Photophobia
• Ocular pain
• Redness
• Scotoma
• Metamorphopsia
• Reduced color vision
• Sudden or progressive visual loss

Disease may be:

• Unilateral
• Bilateral
• Asymmetric

Important Clinical Principle

Syphilis can imitate almost any form of uveitis.

Therefore:

Syphilis testing should be considered in essentially all unexplained uveitis, particularly posterior or panuveitis.

Anterior Segment Manifestations

Possible findings include:

• Granulomatous anterior uveitis
• Non-granulomatous anterior uveitis
• Keratic precipitates
• Iris nodules
• Posterior synechiae
• Elevated IOP
• Scleritis
• Episcleritis

Interstitial Keratitis

Classically associated with congenital syphilis.

Features may include:

• Stromal corneal inflammation
• Corneal vascularization
• Photophobia
• Reduced vision

After inflammation resolves, residual:

Ghost vessels

may remain in the corneal stroma.

Vitreous Involvement

Syphilitic posterior disease commonly produces:

• Vitritis
• Haze
• Inflammatory cells

The amount of vitritis may vary considerably.

Posterior Segment Manifestations

Syphilis may produce:

• Retinitis
• Chorioretinitis
• Retinal vasculitis
• Retinal vascular occlusion
• Neuroretinitis
• Optic neuritis
• Optic disc edema
• Exudative retinal detachment
• Placoid chorioretinitis

Acute Syphilitic Posterior Placoid Chorioretinitis

A particularly characteristic manifestation is:

Acute syphilitic posterior placoid chorioretinitis (ASPPC)

Typical appearance:

• Large
• Yellow-gray
• Placoid lesion
• At or near the macula
• Often involving the outer retina and RPE

ASPPC should strongly raise suspicion for syphilis.

OCT Findings in ASPPC

OCT may show:

• Disruption of the ellipsoid zone
• Outer retinal abnormalities
• RPE irregularity
• Hyperreflective material at the RPE/photoreceptor interface
• Later restoration with successful treatment

Fluorescein Angiography

FA may demonstrate:

• Early hypofluorescence
• Late staining
• Retinal vascular leakage
• Optic disc leakage
• Vasculitis

Indocyanine Green Angiography

ICG may demonstrate areas of:

• Choroidal hypofluorescence
• Choriocapillaris involvement

in selected posterior cases.

Fundus Autofluorescence

May help demonstrate:

• RPE disturbance
• Extent of placoid lesions
• Evolution with treatment

Retinal Vasculitis

Syphilitic vasculitis may involve:

• Arteries
• Veins
• Both

It can lead to:

• Vascular occlusion
• Retinal ischemia
• Neovascular complications

Optic Nerve Manifestations

Possible manifestations include:

• Optic neuritis
• Optic perineuritis
• Neuroretinitis
• Papillitis
• Optic disc edema
• Optic atrophy

MRI may be useful when optic nerve or central neurologic involvement is suspected.

Pupillary Findings

The classic Argyll Robertson pupil:

• Accommodates to near
• Reacts poorly or not at all to light

It is historically associated with neurosyphilis but is uncommon in modern practice.

Cranial Neuropathies

Neurosyphilis may produce:

• Oculomotor nerve palsy
• Trochlear nerve palsy
• Abducens nerve palsy
• Other neurologic deficits

Diagnosis

Diagnosis combines:

• Compatible ocular findings
• Syphilis serology
• Exclusion of important mimics

No single ocular appearance confirms syphilis.

Serologic Testing

Testing generally includes both:

1. Nontreponemal test
2. Treponemal test

Nontreponemal Tests

Examples:

• RPR
• VDRL

These provide a quantitative titer and are useful for monitoring treatment response.

Nontreponemal Titers

A clinically meaningful change is generally:

Fourfold change in titer

For example:

• 1:32 → 1:8 = fourfold decline
• 1:8 → 1:32 = fourfold rise

Titers are therefore useful for:

• Monitoring therapy
• Detecting reinfection
• Detecting treatment failure

False-Positive Nontreponemal Tests

False-positive results may occur with:

• Autoimmune disease
• Pregnancy
• Infection
• Older age
• Other inflammatory states

Therefore, reactive nontreponemal testing requires confirmation with a treponemal assay.

Prozone Phenomenon

Very high antibody concentrations may rarely cause a falsely negative nontreponemal test.

If clinical suspicion is strong despite a negative RPR/VDRL, the laboratory can repeat testing using:

Serial dilution

to exclude a prozone effect.

Treponemal Tests

Examples include:

• TP-PA
• FTA-ABS
• Treponemal enzyme immunoassays
• Chemiluminescent immunoassays

These usually remain positive indefinitely after infection.

Therefore:

Treponemal tests should not be used to monitor treatment response.

Reverse-Sequence Screening

Many laboratories now begin with a:

Treponemal immunoassay

followed by quantitative RPR or VDRL.

Discordant results may require a second treponemal test such as TP-PA.

HIV Testing

All patients diagnosed with ocular syphilis should be offered:

HIV testing

because coinfection is important for:

• Overall management
• STI counseling
• Follow-up

Other STI screening should also be considered.

Lumbar Puncture

Older recommendations favored lumbar puncture in virtually all ocular syphilis.

Modern practice is more selective.

When CSF Examination Is Indicated

Lumbar puncture is particularly appropriate when there are:

• Cranial nerve abnormalities
• Meningeal symptoms
• Cognitive changes
• Motor or sensory deficits
• Other neurologic manifestations

CSF evaluation typically includes:

• Cell count
• Protein
• CSF-VDRL

Isolated Ocular Syphilis

If a patient has:

• Reactive syphilis serology
• Confirmed ocular abnormalities
• No neurologic findings

CSF examination is not required before treatment.

Most importantly:

Treatment should not be delayed for lumbar puncture.

CSF-VDRL

CSF-VDRL is:

• Highly specific
• Relatively insensitive

Therefore, a positive result strongly supports neurosyphilis, but a negative result does not completely exclude it.

Neuroimaging

MRI brain and/or orbits may be useful when there is:

• Optic neuropathy
• Cranial nerve palsy
• Focal neurologic deficit
• Concern for CNS disease

Differential Diagnosis

Because syphilis is a great masquerader, the differential is broad.

Consider:

• Sarcoidosis
• Tuberculosis
• Toxoplasmosis
• Acute retinal necrosis
• CMV retinitis
• Behçet disease
• VKH
• HLA-B27-associated uveitis
• Intermediate uveitis
• APMPPE
• Other white-dot syndromes
• Lyme disease
• Fungal endophthalmitis
• Toxocariasis
• Primary vitreoretinal lymphoma

Treatment

Critical Principle

All ocular syphilis should be treated using a neurosyphilis regimen.

Do not use standard single-dose benzathine penicillin treatment alone for active ocular syphilis.

First-Line Treatment

The preferred regimen is:

Aqueous crystalline penicillin G

Total:

18–24 million units/day IV

administered as:

• 3–4 million units IV every 4 hours

or

• Continuous infusion

for:

10–14 days

Alternative Penicillin Regimen

If reliable adherence can be ensured:

• Procaine penicillin G 2.4 million units IM once daily
• Plus probenecid 500 mg orally four times daily

for:

10–14 days

Additional Benzathine Penicillin

Because neurosyphilis regimens are shorter than those used for late latent syphilis, clinicians may consider:

Benzathine penicillin G 2.4 million units IM weekly for 1–3 weeks

after completion of neurosyphilis therapy in selected patients, particularly when the underlying stage would otherwise require a longer course.

Penicillin Allergy

For nonpregnant patients with penicillin allergy, an alternative that may be considered is:

Ceftriaxone 1–2 g IM or IV daily for 10–14 days

However, evidence is less extensive than for penicillin.

If there is concern about ceftriaxone safety or reliability of alternative therapy:

• Penicillin allergy testing
• Desensitization

should be considered.

Pregnancy

Pregnant patients with syphilis should receive:

Penicillin

because penicillin is the only proven treatment that reliably treats maternal infection and prevents fetal syphilis.

Patients with true penicillin allergy should undergo:

Desensitization followed by penicillin therapy

HIV Coinfection

People with HIV and ocular syphilis are treated with the:

Same neurosyphilis regimen

as patients without HIV.

HIV status does not justify using a less intensive regimen.

Adjunctive Corticosteroids

Corticosteroids may be used to control severe ocular inflammation.

Options include:

• Topical corticosteroids
• Systemic corticosteroids
• Selected periocular therapy

However:

Antibiotic therapy is the essential treatment.

Corticosteroids should not substitute for adequate antimicrobial therapy.

Evidence for Steroids

Systemic corticosteroids are frequently used in severe:

• Posterior uveitis
• Optic neuritis
• Marked inflammatory disease

but controlled evidence proving additional benefit is limited.

If used, they should generally be administered:

With or after initiation of appropriate antibiotic therapy

rather than as isolated immunosuppression.

Cycloplegics

For anterior uveitis, cycloplegics may be used to:

• Relieve ciliary spasm
• Reduce pain
• Prevent posterior synechiae

Examples include:

• Cyclopentolate
• Homatropine
• Atropine in severe inflammation

Intravitreal Therapy

Intravitreal antimicrobial treatment is not routinely necessary when appropriate systemic penicillin therapy is given.

It may be considered only in unusual severe circumstances under specialist care.

Jarisch-Herxheimer Reaction

A Jarisch-Herxheimer reaction may occur within approximately 24 hours after treatment begins.

Features include:

• Fever
• Chills
• Headache
• Myalgia
• Temporary worsening of syphilitic lesions

It results from the inflammatory response to rapid spirochetal killing.

Management is generally:

Supportive

It is not a penicillin allergy.

Ocular Jarisch-Herxheimer Reaction

Rarely, ocular inflammation may transiently worsen after therapy begins.

Close observation is appropriate in patients with severe posterior disease or optic nerve involvement.

Congenital Syphilis

Congenital syphilis treatment depends on:

• Infant age
• Maternal treatment
• Neonatal examination
• Serology
• CSF evaluation

A commonly used regimen for confirmed or highly probable neonatal congenital syphilis is:

Aqueous crystalline penicillin G 50,000 units/kg/dose IV

given:

• Every 12 hours during the first 7 days of life
• Then every 8 hours

for a total of:

10 days

Alternative neonatal regimens are determined by pediatric infectious-disease protocols.

Partner Management

Sex partners require:

• Evaluation
• Serologic testing
• Treatment when indicated

This is essential to prevent:

• Reinfection
• Continued transmission

Public Health Considerations

Syphilis is a reportable infection in many jurisdictions.

Management may involve:

• Public health notification
• Partner services
• STI counseling

Follow-Up

Ophthalmic Follow-Up

Serial examination should assess:

• Visual acuity
• Anterior chamber inflammation
• Vitritis
• Retinitis
• Vasculitis
• Macular involvement
• Optic nerve function

Serologic Follow-Up

Treatment response is monitored with:

Quantitative RPR or VDRL titers

Use the same type of test when possible because RPR and VDRL titers are not directly interchangeable.

Expected Response

A favorable response generally includes:

• Clinical improvement
• Falling nontreponemal titers

A fourfold decline is a commonly used marker of adequate serologic response, although the expected timing varies with syphilis stage.

Serofast State

Some successfully treated patients remain persistently reactive at a low titer.

This is called:

Serofast

and does not automatically indicate treatment failure.

Interpretation depends on:

• Initial stage
• Initial titer
• Clinical response
• Reinfection risk

Treatment Failure or Reinfection

Consider further evaluation when there is:

• Recurrent ocular inflammation
• New syphilitic symptoms
• Sustained fourfold rise in RPR/VDRL titer
• Inadequate expected serologic response
• New exposure

Repeat Lumbar Puncture

Routine repeat CSF examination is generally unnecessary when there is:

• Appropriate clinical improvement
• Appropriate serologic response

unless neurologic or ocular findings fail to improve or recur.

Referral

Management should involve:

• Ophthalmology/uveitis specialist
• Infectious disease or sexual health specialist when appropriate

Neurology consultation may be useful when there are:

• Cranial neuropathies
• Cognitive changes
• Other neurologic manifestations

Patient Education

Patients should understand:

• Syphilis is treatable.
• Ocular syphilis requires intensive systemic therapy.
• Sexual partners may also require testing and treatment.
• Reinfection is possible.
• Follow-up blood testing is essential.
• HIV and other STI testing should be performed.

Prognosis

Visual prognosis depends on:

• Severity at presentation
• Duration before treatment
• Macular involvement
• Optic nerve involvement
• Degree of retinal ischemia
• Promptness of therapy

Early diagnosis and appropriate treatment often produce substantial visual recovery.

Poor Prognostic Features

Potentially unfavorable findings include:

• Severe visual loss at presentation
• Optic neuropathy
• Macular involvement
• Extensive retinitis
• Retinal vascular occlusion
• Delayed treatment
• Permanent retinal or optic nerve atrophy

Complications

Possible ocular complications include:

• Corneal scarring
• Cataract
• Secondary glaucoma
• Posterior synechiae
• Cystoid macular edema
• Retinal vascular occlusion
• Retinal detachment
• Macular atrophy
• Optic atrophy
• Permanent visual loss

Ophthalmology Pearls

• Syphilis is the “great masquerader” and can mimic almost any form of uveitis.
• Ocular syphilis can occur during any stage of systemic infection.
• All ocular syphilis should be treated with a neurosyphilis regimen, regardless of CSF findings.
• The preferred treatment is IV aqueous crystalline penicillin G for 10–14 days.
• A single IM dose of benzathine penicillin appropriate for uncomplicated early syphilis is not adequate treatment for active ocular syphilis.
• Acute syphilitic posterior placoid chorioretinitis is a particularly characteristic posterior manifestation.
• Diagnosis requires both a treponemal test and a quantitative nontreponemal test.
• RPR/VDRL is used for treatment monitoring; treponemal tests generally remain reactive and should not be used to monitor response.
• CSF examination is important when neurologic abnormalities are present, but isolated confirmed ocular disease does not require lumbar puncture before treatment.
• All patients should be tested for HIV and considered for other STI screening.
• Corticosteroids may control inflammation, but adequate antimicrobial treatment is the essential therapy.
• A Jarisch-Herxheimer reaction may temporarily worsen systemic or ocular inflammation after treatment begins.
• Prompt diagnosis is critical because syphilitic ocular disease is often highly treatable before irreversible retinal or optic nerve damage occurs.

Ophthalmology – Ocular Surface Squamous Neoplasia (OSSN)

Basics

Description

Ocular surface squamous neoplasia (OSSN) describes a spectrum of dysplastic and malignant squamous epithelial lesions involving the:

• Conjunctiva
• Cornea
• Limbus

The spectrum includes:

• Mild epithelial dysplasia
• Moderate/severe dysplasia
• Carcinoma in situ
• Invasive squamous cell carcinoma (SCC)

The modern concept is that OSSN represents a continuum from intraepithelial disease to stromal invasion.

⸻

Key Pathologic Distinction

Intraepithelial OSSN

Abnormal squamous cells remain confined above the epithelial basement membrane.

This includes:

• Mild dysplasia
• Moderate dysplasia
• Severe dysplasia
• Carcinoma in situ

Historically these lesions were often called:

Conjunctival intraepithelial neoplasia (CIN)

⸻

Invasive Squamous Cell Carcinoma

Invasive SCC occurs when atypical epithelial cells:

Breach the basement membrane and invade the underlying substantia propria or deeper tissues.

Advanced tumors may invade:

• Sclera
• Cornea
• Anterior chamber
• Orbit

Regional or distant metastasis is uncommon but possible.

⸻

Epidemiology

OSSN is one of the most common malignant tumors of the ocular surface.

Incidence varies markedly by:

• Geographic region
• Ultraviolet exposure
• HIV prevalence
• Population demographics

It is more common in:

• Older adults in temperate regions
• Younger adults in high-UV regions with HIV-associated disease

⸻

Risk Factors

Important risk factors include:

• Chronic ultraviolet-B exposure
• Increasing age
• Male sex in many populations
• Light skin pigmentation
• Smoking
• HIV infection
• Systemic immunosuppression
• Organ transplantation
• Xeroderma pigmentosum
• Chronic ocular surface disease

⸻

HPV

Human papillomavirus, particularly high-risk types such as:

• HPV 16
• HPV 18

has been detected in some OSSN lesions.

However:

The strength of the association varies between studies and geographic populations.

HPV is not considered necessary for development of OSSN.

⸻

Genetics and Molecular Biology

UV-induced DNA damage is believed to be an important mechanism.

Molecular alterations may involve:

• TP53
• Cell-cycle dysregulation
• Abnormal epithelial proliferation

Chronic UV exposure can produce characteristic DNA damage within ocular surface epithelial cells.

⸻

Pathophysiology

OSSN develops through progressive epithelial dysplasia.

A simplified sequence is:

UV or other carcinogenic injury → epithelial DNA damage → dysplasia → carcinoma in situ → invasive SCC

Immunosuppression can reduce normal immune surveillance and accelerate tumor development.

⸻

Associated Conditions

Important associations include:

• HIV/AIDS
• Organ transplantation
• Chronic systemic immunosuppression
• Xeroderma pigmentosum
• Atopic disease
• Other UV-related cutaneous malignancies

⸻

Prevention

Risk reduction includes:

• UV-blocking sunglasses
• Brimmed hats
• Smoking cessation
• Appropriate management of immunosuppression when possible

No strategy completely prevents OSSN.

⸻

Clinical Presentation

Patients may be asymptomatic or report:

• Ocular irritation
• Foreign-body sensation
• Redness
• Visible conjunctival lesion
• Persistent “pterygium”
• Decreased vision if the cornea or visual axis is involved

⸻

Typical Location

OSSN most commonly develops in the:

Interpalpebral limbal region

especially at the:

• Temporal limbus
• Nasal limbus

This distribution reflects chronic UV exposure.

⸻

Clinical Appearance

Conjunctival lesions may appear:

• Gelatinous
• Papilliform
• Leukoplakic
• Nodular
• Sessile
• Diffuse

They may be:

• Amelanotic
• Partially pigmented

⸻

Leukoplakia

A white surface plaque represents:

Hyperkeratosis

and is commonly seen in OSSN.

Marked leukoplakia may obscure underlying vascularity.

⸻

Corneal Extension

Corneal involvement often appears as:

• Gray-white epithelial opacity
• Translucent epithelial sheet
• Irregular or feathery margins
• Pseudopod-like epithelial extensions

Corneal disease remains superficial until invasive disease penetrates deeper layers.

⸻

Feeder Vessels

Prominent feeder vessels may occur.

Large or rapidly growing vessels may increase suspicion for:

• Invasive SCC
• Larger tumor burden

⸻

Signs Suggesting Invasion

Features concerning for invasive disease include:

• Fixed lesion
• Nodularity
• Marked thickness
• Scleral adherence
• Large feeder vessels
• Significant keratinization
• Intraocular inflammation
• Secondary glaucoma
• Orbital extension

⸻

Important Clinical Principle

CIN/carcinoma in situ and invasive SCC cannot be reliably distinguished by appearance alone.

Histopathology remains the gold standard when invasion is suspected.

⸻

Examination

A complete ocular surface examination should include:

• Visual acuity
• Slit-lamp evaluation
• Eyelid eversion
• Careful limbal examination
• Corneal assessment
• Palpation if a nodular lesion is present
• Regional lymph node examination in advanced disease

⸻

Gonioscopy

Gonioscopy is indicated when there is concern for intraocular extension.

Look for:

• Angle involvement
• Abnormal tissue
• Secondary glaucoma
• Anterior chamber invasion

⸻

Intraocular Invasion Warning

In a patient with known or suspected invasive OSSN, the combination of:

• Uveitis
• Elevated IOP
• Anterior chamber mass
• Persistent inflammation

should raise concern for:

Intraocular tumor extension

until proven otherwise.

⸻

Anterior Segment OCT

High-resolution anterior segment OCT is now one of the most useful noninvasive tools for OSSN.

Typical features include:

• Thickened hyperreflective epithelium
• Abrupt transition from normal to abnormal epithelium
• Sharp epithelial demarcation
• Shadowing in thick lesions

AS-OCT is useful for:

• Supporting diagnosis
• Defining tumor extent
• Monitoring response to topical therapy
• Detecting subclinical residual disease

⸻

Ultrasound Biomicroscopy

UBM may help when there is concern for:

• Deep stromal invasion
• Scleral involvement
• Intraocular extension
• Ciliary body involvement

It is especially useful for thicker limbal lesions.

⸻

Impression Cytology

Impression cytology may detect atypical epithelial cells.

It can be useful when:

• A noninvasive diagnostic approach is desired
• Disease is diffuse
• Topical therapy is being considered

However:

It cannot reliably assess stromal invasion.

Therefore, suspicious invasive lesions require biopsy.

⸻

Histopathology

Mild Dysplasia

Atypical cells occupy:

• Lower portions of the epithelium

with partial loss of maturation.

⸻

Severe Dysplasia / Carcinoma in Situ

Atypical cells involve:

Full thickness of the epithelium

without penetration through the basement membrane.

⸻

Invasive SCC

Shows:

• Squamous atypia
• Dyskeratosis
• Keratinization
• Invasion into underlying stroma

⸻

Rare Aggressive Variants

Mucoepidermoid Carcinoma

May demonstrate:

• Squamous differentiation
• Mucin-producing cells
• Greater tendency for deeper invasion

⸻

Spindle Cell / Sarcomatoid SCC

This variant may show:

• Spindle-shaped malignant cells
• More aggressive local behavior
• Higher metastatic potential

⸻

HIV Testing

Consider HIV testing particularly in:

• Younger patients
• Aggressive OSSN
• Multifocal disease
• Patients with other signs of immunosuppression

⸻

Differential Diagnosis

Benign Mimics

• Pterygium
• Pinguecula
• Papilloma
• Pyogenic granuloma
• Conjunctivitis
• Conjunctival nevus
• Limbal dermoid

⸻

Malignant Mimics

• Amelanotic melanoma
• Conjunctival melanoma
• Sebaceous carcinoma with pagetoid spread
• Lymphoma
• Metastatic tumor

⸻

OSSN vs Pterygium

Features favoring OSSN include:

• Irregular thickened epithelium
• Leukoplakia
• Prominent feeder vessel
• Gelatinous appearance
• Atypical corneal epithelial extension
• Abrupt epithelial transition on AS-OCT

A recurrent or atypical “pterygium” should be evaluated carefully.

⸻

Treatment Principles

Treatment depends on:

• Tumor size
• Thickness
• Location
• Circumferential limbal involvement
• Suspicion for invasion
• Prior recurrence
• Patient adherence
• Ability to follow closely

Modern treatment includes both:

• Surgical excision
• Topical medical therapy

Topical therapy is now an established treatment for many superficial OSSN lesions.

⸻

Surgical Excision

Localized or invasive-appearing lesions are often treated with:

Excisional biopsy using a no-touch technique

Goals include:

• Diagnostic confirmation
• Complete tumor removal
• Minimal manipulation of the tumor surface

⸻

No-Touch Technique

Typical principles include:

• Avoid direct manipulation of tumor
• Wide enough clinically clear conjunctival margins
• Superficial keratectomy for corneal component
• Removal of involved superficial sclera if necessary
• Adjunctive cryotherapy to conjunctival margins

⸻

Surgical Margins

Traditional excisions often use several millimeters of clinically normal tissue.

Margin width is individualized according to:

• Tumor size
• Suspicion of invasion
• Anatomic constraints

Excessively wide excision should be avoided when it would create unnecessary limbal stem cell deficiency.

⸻

Cryotherapy

Double freeze-thaw cryotherapy may be applied to:

• Conjunctival margins

to reduce recurrence from microscopic residual disease.

Care must be taken to avoid excessive tissue damage.

⸻

Ocular Surface Reconstruction

Large excisions may require:

• Amniotic membrane graft
• Conjunctival autograft
• Other ocular surface reconstruction

This helps reduce:

• Scarring
• Symblepharon
• Limbal stem cell deficiency

⸻

Topical Therapy

Topical treatment may be used:

• As primary therapy
• Before surgery to shrink a lesion
• After incomplete excision
• For recurrent disease
• For multifocal or diffuse disease

Major agents include:

• 5-fluorouracil
• Mitomycin C
• Interferon alfa-2b

⸻

5-Fluorouracil

Topical 5-FU 1% is widely used.

A common regimen is:

• Four times daily
• Given in treatment cycles

Advantages include:

• Relatively inexpensive
• Effective for broad epithelial disease
• Useful for diffuse lesions

Potential adverse effects include:

• Ocular irritation
• Epitheliopathy
• Conjunctivitis
• Keratitis

⸻

Mitomycin C

Topical MMC is highly effective.

Common concentrations include:

• 0.02%
• 0.04%

Usually given in cycles rather than continuously.

Potential toxicity includes:

• Significant conjunctivitis
• Epitheliopathy
• Punctal stenosis
• Limbal stem cell deficiency
• Scleral complications

Therefore:

MMC is effective but generally more toxic to the ocular surface than 5-FU or interferon.

⸻

Interferon Alfa-2b

Interferon alfa-2b has historically been used as:

• Topical drops
• Perilesional/subconjunctival injection

Advantages include relatively low ocular surface toxicity.

Adverse effects may include:

• Follicular conjunctivitis
• Local irritation
• Flu-like symptoms with injections

Availability has become limited in some regions, so 5-FU is often used more commonly today.

⸻

Choice of Topical Agent

A practical approach:

• 5-FU → inexpensive, effective, commonly available
• MMC → potent but more toxic
• Interferon → well tolerated but availability/cost may limit use

Choice depends on:

• Tumor characteristics
• Patient tolerance
• Cost
• Availability
• Physician experience

⸻

Medical Therapy and Invasive Disease

Topical agents treat:

Epithelial disease

but penetrate poorly into deeply invasive tumor.

Therefore:

Suspected invasive SCC should generally be biopsied and managed surgically and/or with additional oncologic therapy rather than topical therapy alone.

⸻

Monitoring During Topical Therapy

Follow-up should assess:

• Clinical tumor regression
• Corneal involvement
• Limbal disease
• Toxicity
• Residual subclinical epithelium

AS-OCT is particularly useful for detecting persistent disease beneath a clinically normal-looking surface.

⸻

Plaque Brachytherapy

Plaque radiotherapy may be considered for selected:

• Deep scleral invasion
• Intraocular extension
• Recurrent invasive disease

It is not routine for uncomplicated superficial OSSN.

⸻

Intraocular Invasion

Extensive intraocular involvement may require:

• Plaque radiotherapy
• Enucleation in severe cases

Management should involve ocular oncology.

⸻

Orbital Invasion

Extensive orbital spread may require:

• Radical surgery
• Radiation
• Systemic oncologic therapy

Exenteration is now reserved for selected advanced cases.

⸻

Regional Metastasis

Advanced SCC may spread to:

• Preauricular lymph nodes
• Submandibular lymph nodes
• Cervical nodes
• Parotid nodes

Distant metastasis is rare but can involve:

• Lung
• Bone
• Other organs

⸻

Lymph Node Evaluation

Regional node evaluation should be considered in:

• Large invasive SCC
• Recurrent aggressive disease
• Immunosuppressed patients
• Tumors with orbital invasion
• Poorly differentiated histology

⸻

Follow-Up

Long-term surveillance is necessary because recurrence may occur years later.

Follow-up is generally more frequent during the first:

1–2 years

when recurrence risk is highest.

⸻

During Topical Therapy

Patients may require review every:

4–8 weeks

depending on:

• Response
• Toxicity
• Treatment regimen

⸻

After Resolution

Once clinically resolved, patients should continue periodic examinations for:

• Local recurrence
• New OSSN
• Regional lymphadenopathy
• Treatment complications

Long-term follow-up is particularly important for:

• Immunosuppressed patients
• Recurrent disease
• Positive surgical margins
• Invasive SCC

⸻

Recurrence

Risk of recurrence is increased by:

• Positive surgical margins
• Multifocal disease
• Large tumor size
• Tarsal involvement
• Immunosuppression
• Lack of adjunctive therapy
• Invasive histology

Modern adjunctive topical therapy and cryotherapy have reduced recurrence rates compared with older excision-only series.

⸻

Prognosis

Overall prognosis is generally:

Excellent for localized epithelial disease

when properly treated.

Most lesions can be controlled with:

• Surgery
• Topical therapy
• Combination treatment

⸻

Poor Prognostic Features

More concerning features include:

• Large tumor
• Recurrent tumor
• Deep stromal invasion
• Scleral invasion
• Intraocular extension
• Orbital extension
• Aggressive histologic subtype
• Immunosuppression

⸻

Complications

Disease-Related

• Recurrence
• Corneal invasion
• Scleral invasion
• Intraocular extension
• Orbital invasion
• Rare regional or distant metastasis

⸻

Surgical Complications

Possible complications include:

• Limbal stem cell deficiency
• Conjunctival scarring
• Symblepharon
• Persistent epithelial defect
• Corneal scarring
• Dry eye

⸻

Medical Treatment Complications

Possible adverse effects include:

• Conjunctivitis
• Epitheliopathy
• Keratitis
• Limbal stem cell toxicity
• Punctal stenosis, particularly with MMC

⸻

Ophthalmology Pearls

• OSSN is a spectrum from epithelial dysplasia to invasive squamous cell carcinoma.
• The classic lesion occurs at the interpalpebral limbus and may be gelatinous, papilliform, or leukoplakic.
• Leukoplakia represents surface keratinization.
• UV exposure is one of the strongest established risk factors.
• HIV and systemic immunosuppression increase risk, particularly in younger patients.
• CIN/carcinoma in situ cannot reliably be distinguished from invasive SCC by appearance alone.
• High-resolution anterior segment OCT typically shows a thickened hyperreflective epithelium with an abrupt transition from normal tissue and is very useful for diagnosis and follow-up.
• Localized suspicious lesions are commonly managed with no-touch excisional biopsy plus adjunctive cryotherapy.
• 5-FU, mitomycin C, and interferon alfa-2b are established topical treatments for superficial OSSN.
• Topical chemotherapy treats epithelial disease but should not substitute for biopsy when deep invasion is suspected.
• Uveitis or secondary glaucoma in a patient with invasive OSSN should raise concern for intraocular extension.
• Positive margins, immunosuppression, and invasive disease increase recurrence risk.
• Long-term follow-up is required because recurrence may occur years after apparent cure.

Ophthalmology – Ocular Ischemic Syndrome

Basics

Description

Ocular ischemic syndrome (OIS) is a spectrum of anterior and posterior segment abnormalities caused by chronic ocular hypoperfusion, most commonly from severe carotid occlusive disease.

It may affect:

• Retina
• Choroid
• Optic nerve
• Iris
• Ciliary body
• Anterior segment
• Orbit in very severe cases

The most common symptoms are:

• Progressive monocular visual loss
• Ocular or orbital pain

OIS is particularly important because it is a marker of severe systemic vascular disease and is associated with increased risk of:

• Stroke
• Myocardial infarction
• Cardiovascular death

Epidemiology

OIS is relatively uncommon but probably underdiagnosed.

Estimated incidence is approximately:

7–8 cases per million persons per year

Typical demographics include:

• Mean age around 65 years
• Usually age 50–80 years
• Male predominance, reflecting atherosclerotic vascular disease

Bilateral disease occurs in a minority of patients.

Risk Factors

Major risk factors are those for systemic atherosclerosis, including:

• Hypertension
• Diabetes mellitus
• Hyperlipidemia
• Smoking
• Coronary artery disease
• Peripheral vascular disease
• Previous TIA
• Previous stroke
• Advanced age

Pathophysiology

The fundamental mechanism is:

Reduced carotid/ophthalmic arterial flow + inadequate collateral circulation → chronic ocular hypoperfusion

This results in:

• Retinal ischemia
• Choroidal ischemia
• Ciliary body ischemia
• Anterior segment ischemia
• VEGF production
• Retinal and iris neovascularization

Severe ischemia may ultimately produce:

• Neovascular glaucoma
• Retinal vascular insufficiency
• Hypotony
• Profound visual loss

Etiology

Carotid Occlusive Disease

The most common cause is severe atherosclerotic disease of the carotid circulation.

Most commonly involved:

1. Internal carotid artery
2. Common carotid artery
3. Less commonly external carotid collateral pathways

Historically, OIS is most often associated with very high-grade carotid stenosis or complete occlusion.

However, the clinical severity depends not only on the percentage of stenosis but also on:

Adequacy of collateral circulation

Therefore, OIS can occasionally occur with less dramatic stenosis when collateral flow is poor.

Other Causes

Less common causes include:

• Ophthalmic artery occlusive disease
• Giant cell arteritis
• Takayasu arteritis
• Aortic arch disease
• Other large-vessel vasculitis
• Severe systemic hypotension
• Rare hypercoagulable or vaso-occlusive disorders

Commonly Associated Conditions

Frequently associated systemic diseases include:

• Hypertension
• Diabetes mellitus
• Coronary artery disease
• Previous stroke or TIA
• Peripheral arterial disease
• Dyslipidemia

Diagnosis

OIS should be suspected when an older patient with vascular risk factors develops:

• Unilateral progressive visual loss
• Ocular ache
• Midperipheral retinal hemorrhages
• Narrow retinal arteries
• Iris neovascularization
• Delayed choroidal filling on angiography

History

Visual Loss

Visual loss is the most common symptom.

It may be:

• Gradual over weeks to months
• Progressive
• Occasionally abrupt

Many patients present with visual acuity worse than:

20/60

Visual loss may arise from:

• Macular ischemia
• Retinal ischemia
• Neovascular glaucoma
• Cataract
• Optic nerve ischemia
• Retinal artery occlusion

Transient Monocular Visual Loss

Some patients experience:

Amaurosis fugax

This may present as:

• Transient dimming
• Curtain-like visual loss
• Brief monocular blindness

This should raise concern for significant carotid vascular disease.

Delayed Recovery After Bright Light

A characteristic symptom is:

Prolonged recovery of vision after exposure to bright light

The ischemic retina requires abnormally long to recover after photoreceptor bleaching.

This is an important clue to ocular hypoperfusion.

Ocular Pain

Approximately one-third to nearly one-half of patients experience:

Dull ocular or periorbital pain

Sometimes termed:

Ocular angina

Pain may result from:

• Ocular ischemia
• Elevated IOP from neovascular glaucoma

It is often described as:

• Dull
• Constant
• Periorbital or brow ache

Anterior Segment Findings

Possible findings include:

• Conjunctival injection
• Episcleral injection
• Corneal edema
• Descemet folds
• Mild anterior chamber inflammation
• Iris atrophy
• Iris neovascularization
• Posterior synechiae
• Anterior synechiae
• Cataract

Anterior Chamber Inflammation

Mild anterior uveitis may occur.

Typical pattern:

• Relatively prominent flare
• Fewer cells

This reflects ischemic disruption of the blood-aqueous barrier.

Iris Neovascularization

Rubeosis iridis is a major finding.

It results from:

Retinal ischemia → VEGF production → anterior segment neovascularization

It may progress to:

• Angle neovascularization
• Peripheral anterior synechiae
• Neovascular glaucoma

Intraocular Pressure

IOP may be:

• Elevated
• Normal
• Low

Elevated IOP

Usually due to:

• Neovascular glaucoma

Low IOP

May result from:

Ciliary body hypoperfusion and reduced aqueous production

This is an important distinction from many other ischemic retinal conditions.

Hypotony

Severe ciliary body ischemia may cause hypotony.

Consequences include:

• Corneal decompensation
• Cataract
• Hypotony maculopathy
• Progressive structural damage

Pupils

Possible abnormalities include:

• RAPD
• Sluggish response
• Semidilated pupil

depending on the degree of retinal and optic nerve ischemia.

Posterior Segment Findings

Posterior segment abnormalities are extremely important.

Typical findings include:

• Narrowed retinal arteries
• Dilated but relatively non-tortuous retinal veins
• Midperipheral retinal hemorrhages
• Microaneurysms
• Cotton-wool spots
• Retinal neovascularization
• Optic disc neovascularization
• Choroidal ischemia

Retinal Hemorrhages

A classic pattern is:

Dot-blot hemorrhages predominantly in the midperipheral retina

This contrasts with CRVO, where hemorrhages are often:

• More diffuse
• Present in all quadrants
• Associated with more tortuous veins

Retinal Veins

OIS typically shows:

Dilated but not markedly tortuous veins

This is an important clue distinguishing OIS from CRVO.

Microaneurysms

Microaneurysms are often:

• Numerous
• Midperipheral

They may become particularly apparent on fluorescein angiography.

Retinal Arterial Pulsations

Spontaneous retinal arterial pulsation may occur because ocular perfusion pressure is critically low.

Cotton-Wool Spots

Cotton-wool spots may occur from focal retinal nerve fiber layer ischemia.

Choroidal Ischemia

Possible findings include:

• Patchy choroidal nonperfusion
• Peripheral wedge-shaped chorioretinal atrophy
• Delayed choroidal filling on angiography

Retinal and Disc Neovascularization

Chronic retinal ischemia can lead to:

• Neovascularization of the disc
• Neovascularization elsewhere
• Vitreous hemorrhage
• Neovascular glaucoma

Central Retinal Artery Occlusion

A cherry-red spot may occasionally occur if OIS is complicated by:

• Central retinal artery occlusion
• Severe acute arterial hypoperfusion

Orbital Infarction Syndrome

An extreme form of ischemia may involve both:

• Intraocular tissues
• Orbital tissues

Features may include:

• Severe orbital pain
• Ptosis
• Ophthalmoplegia
• Proptosis
• Corneal hypoesthesia
• Intraocular inflammation
• Hypotony

This represents severe compromise of orbital blood supply.

Systemic Examination

Examine for evidence of vascular disease.

Assessment should include:

• Blood pressure
• Peripheral pulses
• Carotid auscultation
• Cardiac examination

However, absence of a carotid bruit does not exclude severe carotid stenosis.

Fluorescein Angiography

FA is one of the most useful ocular diagnostic tests.

Delayed Choroidal Filling

The most characteristic finding is:

Delayed or patchy choroidal filling

This is one of the most specific angiographic signs of OIS.

Prolonged Arteriovenous Transit Time

A highly sensitive finding is:

Prolonged retinal arteriovenous transit

There may be markedly delayed passage of fluorescein from the retinal arteries into the veins.

Additional FA Findings

Other findings include:

• Retinal vascular staining
• Arterial wall staining
• Capillary nonperfusion
• Microaneurysms
• Disc leakage
• Macular leakage
• Slow leading edge of arterial dye

OCT

OCT may demonstrate:

• Macular edema
• Retinal thinning from chronic ischemia
• Inner retinal atrophy
• Secondary epiretinal changes

Macular edema in OIS is less common than in CRVO or diabetic retinopathy.

OCT Angiography

OCTA may help demonstrate:

• Reduced retinal capillary density
• Macular nonperfusion

However, it does not replace systemic vascular imaging.

Indocyanine Green Angiography

ICG may show:

• Delayed arm-to-choroid circulation
• Slow choroidal filling
• Abnormal watershed zones

It can further demonstrate choroidal vascular insufficiency.

Carotid Duplex Ultrasonography

Carotid Doppler ultrasound is commonly the initial noninvasive vascular test.

It evaluates:

• Degree of stenosis
• Flow velocity
• Plaque morphology
• Hemodynamics

Limitations include:

• Calcified plaque
• Tortuous vessels
• High cervical lesions
• Operator dependence

CTA and MRA

CT angiography and MR angiography provide detailed evaluation of:

• Carotid arteries
• Intracranial circulation
• Collateral circulation

These are particularly useful when:

• Duplex findings are inconclusive
• Surgical intervention is being considered
• Intracranial disease is suspected

Ophthalmic Artery Doppler

Retrobulbar Doppler may show:

Reversal of ophthalmic artery flow

This is a strong indicator of severe ipsilateral carotid occlusive disease with collateralization through the external carotid system.

Catheter Angiography

Digital subtraction angiography provides highly detailed vascular imaging but is invasive.

It is generally reserved for cases in which:

• Endovascular intervention is being considered
• Noninvasive imaging is inconclusive

Electroretinography

ERG may demonstrate impairment of both:

• Outer retina → reduced a-wave
• Inner retina → reduced b-wave

This reflects generalized retinal ischemia.

It is rarely needed for routine diagnosis.

Visual-Evoked Potentials

VEP may show:

• Reduced amplitude
• Increased latency

but is nonspecific and rarely central to diagnosis.

Giant Cell Arteritis Evaluation

If OIS-like findings occur in a patient with possible GCA, urgently consider:

• ESR
• CRP
• CBC with platelet count

Particularly ask about:

• New headache
• Jaw claudication
• Scalp tenderness
• Polymyalgia symptoms
• Constitutional symptoms

Differential Diagnosis

The two most important retinal mimics are:

• Central retinal vein occlusion
• Diabetic retinopathy

OIS vs Central Retinal Vein Occlusion

OIS typically shows:

• Narrow retinal arteries
• Dilated but minimally tortuous veins
• Midperipheral dot-blot hemorrhages
• Delayed choroidal filling
• Prolonged AV transit
• Possible low IOP

CRVO typically shows:

• Markedly dilated tortuous veins
• Extensive hemorrhage in all quadrants
• Disc edema
• Frequent macular edema
• Primarily venous outflow obstruction

OIS vs Diabetic Retinopathy

OIS is commonly:

• Unilateral or markedly asymmetric
• Associated with delayed choroidal filling
• Associated with midperipheral hemorrhage predominance

Diabetic retinopathy is usually:

• Bilateral
• More symmetric
• Characterized by posterior-pole microaneurysms and hemorrhages
• Often associated with hard exudates and diabetic macular edema

However, severe carotid disease can make diabetic retinopathy highly asymmetric.

Additional Differential Diagnosis

Consider:

• Ischemic CRVO
• Proliferative diabetic retinopathy
• Hypertensive retinopathy
• Retinal artery occlusion
• Giant cell arteritis
• Takayasu arteritis
• Hyperviscosity retinopathy
• Neovascular glaucoma from another cause

Treatment Principles

Management has three major objectives:

1. Restore or optimize ocular/systemic perfusion where possible
2. Treat retinal ischemia and neovascularization
3. Treat secondary complications such as neovascular glaucoma

Systemic vascular evaluation is essential because OIS often indicates potentially life-threatening vascular disease.

Systemic Vascular Management

All patients should undergo urgent medical evaluation for:

• Carotid disease
• Coronary artery disease
• Stroke risk
• Diabetes
• Hypertension
• Dyslipidemia

Management may include:

• Antiplatelet therapy when appropriate
• Statin therapy
• Blood pressure optimization
• Diabetes control
• Smoking cessation
• Weight management
• Exercise and dietary modification

These decisions should be coordinated with the appropriate medical or vascular team.

Carotid Revascularization

Carotid Endarterectomy

Carotid endarterectomy (CEA) may be indicated in selected patients with significant carotid stenosis, especially when the patient is symptomatic and operative risk is acceptable.

The decision depends on:

• Degree of stenosis
• Whether stenosis is symptomatic
• Overall neurologic risk
• Life expectancy
• Surgical risk
• Vascular anatomy

Because treatment guidelines evolve, these patients require vascular or stroke-specialist assessment rather than relying solely on a fixed percentage threshold.

Carotid Artery Stenting

Carotid artery stenting may be considered when:

• CEA carries excessive risk
• Anatomy is unfavorable for surgery
• Other vascular considerations favor an endovascular approach

Effect of Revascularization on the Eye

Improved carotid flow may:

• Improve ocular perfusion
• Reduce ischemic symptoms
• Reduce neovascular drive

The benefit is generally greatest before irreversible retinal damage or advanced neovascular glaucoma has developed.

Visual recovery is limited once severe retinal or optic nerve ischemia is established.

Panretinal Photocoagulation

PRP is used when there is retinal or anterior segment neovascularization from ischemia.

It can reduce VEGF production and help cause regression of:

• Iris neovascularization
• Disc neovascularization
• Retinal neovascularization

However, PRP may be less effective in OIS than in proliferative diabetic retinopathy because the entire ocular circulation is hypoperfused.

Anti-VEGF Therapy

Intravitreal anti-VEGF agents may produce rapid regression of:

• Iris neovascularization
• Angle neovascularization
• Retinal neovascularization

They may also help macular edema in selected patients.

However:

Anti-VEGF is an adjunct, not treatment of the underlying carotid hypoperfusion.

Its effect on neovascularization may be temporary unless the ischemic drive is also addressed.

Anterior Uveitis

Mild ischemic anterior inflammation may be treated with:

• Topical corticosteroids
• Cycloplegics

Cycloplegics can:

• Reduce ciliary spasm
• Improve pain
• Prevent posterior synechiae

Neovascular Glaucoma

NVG is a major vision-threatening complication.

Treatment includes:

• Anti-VEGF
• PRP when possible
• IOP-lowering therapy
• Anti-inflammatory treatment
• Glaucoma surgery when necessary

IOP-Lowering Medications

Aqueous suppressants are generally preferred:

• Beta-blockers
• Alpha-2 agonists
• Topical carbonic anhydrase inhibitors

Systemic carbonic anhydrase inhibitors may be considered in selected severe cases if medically appropriate.

Pilocarpine

Pilocarpine should generally be avoided in neovascular or inflamed eyes because it:

• Is usually ineffective in synechial angle closure
• Can worsen inflammation
• May increase discomfort

Prostaglandin Analogs

Prostaglandin analogs can lower IOP, but historically have been used cautiously in markedly inflamed ischemic eyes.

In modern practice they may still be considered when additional IOP reduction is needed and inflammation is controlled.

They are not absolutely contraindicated solely because OIS is present.

Glaucoma Surgery

If NVG remains uncontrolled, options include:

• Glaucoma drainage device
• Trabeculectomy in selected quiet eyes
• Cyclophotocoagulation

Tube shunts are often favored in eyes with active or previously active neovascularization.

Cyclodestructive Treatment

Cyclophotocoagulation may be especially useful when:

• Visual potential is poor
• Pain is significant
• IOP is refractory
• Incisional surgery is unlikely to succeed

Hypotony

If IOP is already low because of severe ciliary body ischemia:

IOP-lowering therapy should not be given simply because neovascularization is present.

Treatment must be tailored to the actual pressure and mechanism.

Referral

OIS should trigger multidisciplinary evaluation.

Appropriate referrals may include:

• Retina specialist
• Glaucoma specialist
• Primary care/internal medicine
• Neurology or stroke service
• Vascular surgery
• Cardiology

Urgency

New OIS is not merely an ophthalmic problem.

Because severe carotid disease may be present, patients need prompt systemic vascular assessment.

Urgency is particularly high with:

• Amaurosis fugax
• Recent neurologic symptoms
• Acute visual loss
• Known severe carotid stenosis

Follow-Up

Frequency depends on:

• Retinal ischemia
• Presence of neovascularization
• IOP
• Visual acuity
• Treatment status

Patients with active neovascularization or NVG require close follow-up.

Monitor:

• Iris
• Angle by gonioscopy
• IOP
• Retina
• Optic disc
• Macula

Patient Education

Patients should understand that OIS may represent:

Severe systemic vascular disease

They should seek urgent care for symptoms such as:

• Sudden weakness or numbness
• Facial droop
• Speech difficulty
• Sudden monocular visual loss
• Chest pain
• Severe new neurologic symptoms

Systemic Risk Modification

Long-term care should emphasize:

• Smoking cessation
• Diabetes control
• Blood pressure control
• Lipid management
• Appropriate antiplatelet/statin therapy
• Cardiovascular follow-up

Extreme lowering of systemic blood pressure should be avoided in patients with critically impaired ocular perfusion unless medically necessary.

Prognosis

Visual Prognosis

Visual prognosis is generally:

Guarded to poor

because presentation often occurs after substantial chronic ischemic damage.

Poor prognostic factors include:

• Severe visual loss at presentation
• Iris neovascularization
• Neovascular glaucoma
• Extensive retinal ischemia
• Advanced carotid disease

Once profound ischemic retinal damage has occurred, restoring carotid flow may not restore vision.

Systemic Prognosis

The systemic prognosis is also serious.

OIS is associated with substantial risk of:

• Stroke
• Myocardial infarction
• Cardiovascular death

Therefore, identifying OIS can be life-saving even when ocular visual recovery is limited.

Complications

Ocular complications include:

• Neovascular glaucoma
• Retinal neovascularization
• Vitreous hemorrhage
• Macular edema
• Cataract
• Hypotony
• Corneal decompensation
• Retinal artery occlusion
• Severe permanent visual loss

Systemic complications include:

• Cerebral infarction
• TIA
• Myocardial infarction
• Cardiovascular death

Ophthalmology Pearls

• OIS = chronic ocular hypoperfusion, most commonly from severe carotid occlusive disease.
• Classic presentation: progressive monocular visual loss + dull ocular/orbital pain in an older patient with vascular risk factors.
• Retinal findings classically include narrow arteries, dilated but relatively non-tortuous veins, and midperipheral dot-blot hemorrhages.
• Delayed patchy choroidal filling on fluorescein angiography is one of the most specific signs.
• Prolonged arteriovenous transit time is highly sensitive.
• IOP may be high from neovascular glaucoma or low from ciliary body ischemia.
• Rubeosis in OIS results from severe ischemia and may progress to neovascular glaucoma.
• Unlike CRVO, OIS veins are generally not markedly tortuous, and hemorrhages are often concentrated in the midperiphery.
• Carotid duplex is a common initial vascular study, with CTA/MRA used for further anatomic assessment.
• Anti-VEGF and PRP treat ocular neovascularization but do not correct the underlying carotid hypoperfusion.
• Carotid revascularization is most likely to benefit ocular perfusion before advanced irreversible retinal damage or NVG develops.
• OIS is a marker of potentially life-threatening vascular disease; systemic stroke and cardiovascular evaluation is mandatory.

Ophthalmology – Ocular Hypertension

Basics

Description

Ocular hypertension (OHT) refers to consistently elevated intraocular pressure (IOP) in an eye with:

• Open anterior chamber angles
• No glaucomatous optic nerve damage
• No glaucomatous retinal nerve fiber layer loss
• No corresponding visual field defect
• No secondary ocular cause explaining the elevated IOP

Historically, OHT has often been defined as:

IOP >21 mmHg

However, 21 mmHg is a statistical threshold rather than a strict biologic cutoff.

The key distinction is:

Ocular hypertension = elevated IOP without glaucoma damage.

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Epidemiology

Ocular hypertension is relatively common.

Estimated prevalence among adults older than 40 years is approximately:

4–7%

Only a proportion of patients with OHT eventually develop primary open-angle glaucoma.

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Clinical Importance

OHT itself does not mean that glaucoma is present.

However:

Elevated IOP is the most important modifiable risk factor for developing primary open-angle glaucoma.

Management therefore focuses on determining:

• How high the individual patient’s risk is
• Whether preventive treatment is justified
• How closely the patient should be monitored

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Risk of Conversion to Glaucoma

The landmark Ocular Hypertension Treatment Study (OHTS) identified several major predictors of progression from OHT to primary open-angle glaucoma.

Important risk factors include:

• Increasing age
• Higher baseline IOP
• Larger vertical cup-to-disc ratio
• Higher visual field pattern standard deviation
• Thinner central corneal thickness

The greater the number and severity of these factors, the greater the risk of conversion.

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Central Corneal Thickness

Central corneal thickness is particularly important.

Thin cornea

A thin cornea may:

• Cause Goldmann applanation tonometry to underestimate IOP
• Be associated with a higher independent risk of glaucoma development

Thick cornea

A thick cornea may:

• Produce a higher measured IOP
• Make the apparent ocular hypertension less concerning in some patients

However:

There is no universally reliable formula for mathematically “correcting” IOP according to corneal thickness.

CCT should be interpreted as part of the overall risk profile.

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Additional Risk Considerations

Other factors that may influence the decision to treat include:

• Strong family history of glaucoma
• African ancestry
• Long life expectancy
• Progressive increase in optic nerve cupping
• Disc hemorrhage
• Very high untreated IOP
• Thin cornea
• Suspicious OCT changes
• Reduced ability to attend reliable follow-up

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Genetics

There is no single genetic marker that defines ocular hypertension.

OHT and primary open-angle glaucoma likely share a complex polygenic susceptibility.

Family history remains clinically useful even when molecular testing is not performed.

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Pathophysiology

The exact reason some patients tolerate elevated IOP without optic nerve damage while others develop glaucoma is incompletely understood.

Important factors probably include differences in:

• Lamina cribrosa anatomy
• Optic nerve susceptibility
• Ocular blood flow
• Connective tissue properties
• Retinal ganglion cell resilience
• IOP magnitude and fluctuation

OHT may therefore be considered a risk state, not a disease with established neural injury.

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Etiology

Primary ocular hypertension has no identifiable secondary cause.

Before making the diagnosis, exclude:

• Angle closure
• Pigment dispersion
• Pseudoexfoliation
• Uveitis
• Steroid response
• Ocular trauma
• Previous surgery
• Neovascularization
• Lens-related secondary glaucoma

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Associated Conditions

OHT is associated primarily with:

• Increased risk of primary open-angle glaucoma
• Thick or thin central corneal thickness affecting interpretation of IOP

Some patients have no other ocular or systemic abnormality.

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Diagnosis

OHT is a diagnosis of exclusion.

The patient must have elevated IOP but no demonstrable glaucomatous structural or functional damage.

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History

Patients are usually:

Asymptomatic

Ask about:

• Previous IOP measurements
• Family history of glaucoma
• Steroid use
• Ocular trauma
• Previous ocular surgery
• Uveitis
• Migraine
• Sleep apnea
• Systemic hypertension
• Diabetes
• Medication history

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Visual Symptoms

OHT itself does not usually cause:

• Pain
• Redness
• Visual field loss
• Reduced visual acuity

Symptoms suggest another diagnosis or a complication.

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Examination

Intraocular Pressure

Elevated IOP should be confirmed on more than one occasion whenever practical.

Important considerations include:

• Time of day
• Measurement technique
• Corneal thickness
• Corneal biomechanics
• Patient squeezing
• Breath-holding
• Measurement error

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Diurnal Variation

IOP varies throughout the day.

A patient with apparently mild OHT may have higher IOP outside usual clinic hours.

Repeated measurements at different times may occasionally be useful when:

• IOP is highly variable
• Optic nerve findings are suspicious
• Progression occurs despite apparently acceptable readings

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Gonioscopy

Gonioscopy is essential.

OHT should have:

• Open angles
• No significant peripheral anterior synechiae
• No secondary angle abnormality

Gonioscopy helps exclude:

• Chronic angle closure
• Pigment dispersion
• Pseudoexfoliation
• Angle recession
• Neovascularization
• Inflammatory abnormalities

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Optic Nerve Examination

The optic nerve should show no definite glaucomatous damage.

Assess:

• Cup-to-disc ratio
• Vertical cupping
• Neuroretinal rim thickness
• Rim notching
• Disc hemorrhage
• RNFL defects
• Inter-eye asymmetry

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Suspicious Optic Nerve

Findings such as:

• Focal rim thinning
• Inferotemporal or superotemporal notching
• RNFL wedge defect
• Disc hemorrhage

raise concern that the patient may already have:

Early glaucoma rather than isolated OHT.

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Optical Coherence Tomography

OCT should assess:

• Peripapillary RNFL
• Macular ganglion cell complex
• Ganglion cell–inner plexiform layer
• Optic nerve head

In true OHT, structural testing should remain within expected normal limits and stable over time.

Serial OCT is more useful than a single scan.

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Optic Disc Photography

Baseline optic disc photographs are valuable for detecting future change.

They can document:

• Cup enlargement
• Rim thinning
• New disc hemorrhage
• RNFL changes

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Visual Field Testing

Standard automated perimetry is required to establish that there is no functional glaucomatous loss.

Typical baseline testing includes:

• 24-2
• 24-2C depending on availability

If central damage is suspected, a:

• 10-2 visual field

may be useful.

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Pachymetry

Central corneal thickness should be measured in essentially all patients with OHT.

This helps with:

• IOP interpretation
• Risk stratification

Thin CCT is an important predictor of conversion to glaucoma.

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Differential Diagnosis

Important alternatives include:

• Primary open-angle glaucoma
• Secondary open-angle glaucoma
• Chronic angle-closure glaucoma
• Steroid-induced ocular hypertension
• Pigmentary glaucoma
• Pseudoexfoliative glaucoma
• Uveitic glaucoma
• Angle-recession glaucoma

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Ocular Hypertension vs Primary Open-Angle Glaucoma

Ocular Hypertension

• Elevated IOP
• Open angle
• No optic nerve damage
• No RNFL loss
• No visual field defect