Ophthalmology – Pterygium

Basics

Description

A pterygium is a benign, fibrovascular, wing-shaped growth of bulbar conjunctiva that crosses the limbus and extends onto the cornea.

It most commonly arises:

Nasally within the interpalpebral fissure

and grows toward the visual axis.

Although benign, it can impair vision through:

• Induced astigmatism
• Tear-film disturbance
• Corneal flattening/distortion
• Direct involvement of the visual axis
• Postoperative recurrence

Clinical Importance

Most pterygia are initially:

Observed

Surgery is considered when there is:

• Progressive growth toward the visual axis
• Significant induced astigmatism
• Reduced vision
• Recurrent inflammation or irritation
• Restriction of ocular motility
• Contact lens intolerance
• Significant cosmetic concern
• Suspicion for atypical or neoplastic pathology

Epidemiology

Pterygium is strongly associated with chronic environmental exposure.

It is more common in:

• Tropical and subtropical regions
• Populations living near the equator
• Outdoor workers
• Individuals with prolonged UV exposure

The classic epidemiologic association is sometimes called:

The “pterygium belt”

roughly within 30–40° latitude of the equator.

Risk Factors

Major risk factors include:

• Ultraviolet radiation
• Outdoor occupation
• Wind
• Dust
• Dry environments
• Chronic ocular surface irritation
• Increasing cumulative lifetime exposure

Additional influences may include:

• Genetic susceptibility
• Ocular surface inflammation

UV Radiation

The strongest environmental risk factor is:

Chronic UV-B exposure

UV light may induce:

• Oxidative stress
• Limbal epithelial injury
• Abnormal fibrovascular proliferation
• Matrix remodeling

Prevention

Preventive measures include:

• UV-blocking sunglasses
• Wraparound eyewear
• Wide-brimmed hat
• Protection from excessive wind and dust
• Ocular surface lubrication in dry environments

These measures may reduce:

• New lesion development
• Progression
• Postoperative recurrence risk

Pathophysiology

Pterygium is not simply a passive “degeneration.”

Modern understanding favors an active proliferative process involving:

• UV-induced limbal epithelial damage
• Altered limbal stem-cell function
• Fibroblast activation
• Extracellular matrix remodeling
• Angiogenesis
• Chronic inflammation

There may also be dysregulation of:

• Matrix metalloproteinases
• VEGF
• Transforming growth factor pathways

Histopathology

Typical findings include:

• Elastotic degeneration of conjunctival stroma
• Fibrovascular proliferation
• Abnormal collagen
• Chronic inflammatory cells
• Invasion of superficial cornea

This actinic stromal change is often termed:

Elastotic degeneration

HPV

Human papillomavirus has been detected in some pterygium specimens.

However:

HPV is not considered an established universal cause of pterygium.

Its role remains variable and population-dependent.

Clinical Anatomy

A pterygium has:

• Head – leading edge on cornea
• Neck – region crossing the limbus
• Body – fibrovascular conjunctival portion

Location

Most are:

Nasal

because the nasal interpalpebral limbus receives substantial reflected and peripheral UV exposure.

Less commonly:

• Temporal pterygium
• Double-headed nasal and temporal pterygia

A purely temporal or otherwise atypical lesion deserves closer evaluation for alternative pathology.

Symptoms

Patients may report:

• Redness
• Foreign-body sensation
• Burning
• Irritation
• Dryness
• Intermittent inflammation
• Cosmetic concern
• Blurred vision
• Distorted vision

Visual Loss

Vision may decrease because of:

• Induced astigmatism
• Irregular astigmatism
• Tear-film instability
• Corneal scarring
• Direct encroachment on the visual axis

Visual distortion can occur well before the lesion reaches the pupillary center.

Induced Astigmatism

Pterygium typically produces:

Corneal flattening along the horizontal meridian

which commonly induces:

With-the-rule astigmatism

Increasing lesion size is associated with increasing:

• Astigmatism
• Corneal irregularity

Slit-Lamp Examination

Typical appearance:

• Triangular fibrovascular tissue
• Apex directed centrally
• Body arising from bulbar conjunctiva
• Extension across the limbus onto cornea

Assess:

• Size
• Vascularity
• Thickness
• Corneal extension
• Progression
• Degree of inflammation
• Distance from visual axis

Active / Progressive Appearance

A more active pterygium may appear:

• Thick
• Fleshy
• Hyperemic
• Highly vascular

These lesions are more likely to:

• Progress
• Recur after surgery

Stocker Line

A Stocker line is a line of:

Iron deposition in the corneal epithelium just anterior to the pterygium head

It reflects chronicity and tear-film iron deposition.

It should not be interpreted as a reliable marker that the lesion is completely inactive.

Fuchs Islets

Small gray-white spots near the pterygium head may occasionally represent:

Fuchs islets

and are associated with epithelial changes near the advancing edge.

Diagnosis

Diagnosis is usually:

Clinical

based on slit-lamp appearance.

Routine laboratory testing is unnecessary.

Corneal Topography / Tomography

Topography is useful when assessing:

• Induced astigmatism
• Irregular corneal shape
• Surgical timing
• Preoperative planning

It can demonstrate:

• Horizontal flattening
• Asymmetric astigmatism
• Irregularity extending beyond visible lesion margins

Photography

Serial slit-lamp photography is useful for:

• Documenting size
• Monitoring progression
• Counseling patients

Biopsy / Histopathology

Routine biopsy is not necessary for a classic small pterygium.

However, excised tissue is often submitted for:

Histopathologic examination

especially when the lesion is:

• Atypical
• Leukoplakic
• Nodular
• Rapidly growing
• Unusually vascular
• Temporal
• Recurrent with unusual morphology

This helps exclude:

Ocular surface squamous neoplasia (OSSN).

Differential Diagnosis

Important differentials include:

• Pseudopterygium
• Pinguecula
• Ocular surface squamous neoplasia
• Conjunctival intraepithelial neoplasia
• Squamous cell carcinoma
• Limbal dermoid
• Salzmann nodular degeneration
• Peripheral corneal scar

Pterygium vs Pinguecula

Pinguecula

• Yellow-white elevated conjunctival lesion
• Located adjacent to limbus
• Does not cross onto cornea

Pterygium

• Fibrovascular growth
• Crosses the limbus
• Extends onto cornea

Pterygium vs Pseudopterygium

A pseudopterygium is conjunctival adhesion to the cornea caused by:

• Trauma
• Chemical injury
• Inflammation
• Peripheral corneal ulceration

Unlike a true pterygium:

• It can occur at any limbal location
• It is not necessarily confined to the interpalpebral zone

A probe may sometimes pass beneath portions of the pseudopterygium away from the site of adhesion:

Bowman probe test

though this maneuver is not always necessary.

Pterygium vs OSSN

Features concerning for OSSN include:

• Gelatinous or leukoplakic surface
• Feeder vessels
• Nodularity
• Rapid growth
• Atypical temporal location
• Irregular epithelial thickening

If suspicious:

Do not assume the lesion is a simple pterygium.

Consider:

• High-resolution anterior segment OCT
• Excisional/incisional biopsy
• Histopathology

Medical Treatment

Medical therapy does not remove a pterygium.

Treatment is aimed at:

Symptom control and inflammation reduction.

Lubrication

First-line symptomatic treatment includes:

• Artificial tears
• Lubricating ointment
• Preservative-free preparations when frequent use is needed

These improve:

• Irritation
• Tear-film instability
• Foreign-body sensation

Topical Steroids

A short course of mild topical corticosteroid may be considered for:

• Acute inflammatory flare
• Significant hyperemia
• Irritation

Use should be limited and monitored because of:

• IOP elevation
• Cataract
• Infection risk

Vasoconstrictors

Chronic use of topical vasoconstrictors should generally be:

Avoided

because of:

• Rebound hyperemia
• Tachyphylaxis
• Ocular surface irritation

Surgical Indications

Surgery is indicated when there is:

• Progressive growth toward visual axis
• Reduced visual acuity
• Significant induced astigmatism
• Irregular astigmatism
• Recurrent troublesome inflammation
• Restrictive motility
• Persistent symptoms despite conservative therapy
• Cosmetic concern
• Suspicion for dysplasia or malignancy

Timing of Surgery

Surgery should ideally occur:

Before major central corneal scarring or severe visual-axis involvement develops.

However, proximity to the visual axis alone is not the only criterion.

Increasing:

• Astigmatism
• Corneal distortion

may justify surgery before the lesion reaches the center.

Preferred Surgical Technique

For most primary pterygia, the preferred approach is:

Excision with conjunctival autograft

often including limbal conjunctiva.

This provides:

• Low recurrence
• Good cosmetic result
• Restoration of normal conjunctival anatomy

Conjunctival Autograft

The graft is usually obtained from:

• Superior bulbar conjunctiva

It is placed over the bare scleral defect after excision.

It may be secured with:

• Sutures
• Fibrin glue
• Autologous blood in selected techniques

Fibrin Glue

Potential advantages include:

• Shorter surgery
• Less postoperative discomfort
• Reduced suture-related inflammation

Disadvantages include:

• Cost
• Rare graft displacement
• Potential biologic product concerns depending on preparation

Bare Sclera Technique

Simple excision leaving bare sclera has a:

High recurrence rate

and is generally:

Not recommended as routine primary treatment.

Conjunctival-Limbal Autograft

Including limbal tissue may:

• Restore limbal barrier function
• Reduce recurrence

especially in:

• Young patients
• Aggressive lesions
• Recurrent pterygia

Care must be taken not to damage the donor limbus excessively.

Mitomycin C

Mitomycin C (MMC) can reduce recurrence by inhibiting fibroblast proliferation.

It may be used:

• Intraoperatively
• Occasionally postoperatively in specialized protocols

MMC Risks

MMC must be used cautiously because complications may include:

• Scleral thinning
• Scleral melt
• Delayed epithelial healing
• Corneal toxicity
• Infectious scleritis
• Secondary glaucoma
• Severe ocular surface complications

It is generally reserved for:

• High-risk primary lesions
• Recurrent pterygia
• Selected surgical cases

Amniotic Membrane Transplantation

Amniotic membrane may be used when:

• Conjunctiva must be preserved
• Defect is large
• There is significant ocular surface disease
• Prior surgery limits available conjunctiva

However:

Recurrence is generally higher with amniotic membrane alone than with conjunctival autograft for routine primary pterygium surgery.

Preserving Conjunctiva

Conjunctival preservation may be particularly important in patients who may later need:

• Trabeculectomy
• Glaucoma drainage surgery

In such patients, surgical planning should consider future glaucoma needs.

Postoperative Treatment

Typical postoperative therapy includes:

• Topical antibiotic for a short course
• Topical corticosteroid with gradual taper
• Lubrication

The exact steroid duration depends on:

• Inflammation
• Healing
• Recurrence risk
• Surgical technique

Important Modern Correction – Steroid Duration

A fixed requirement for:

Six months of postoperative topical steroid

is not standard for every patient.

Many patients are treated for:

• Several weeks
• Sometimes a few months

with tapering individualized to inflammation and recurrence risk.

Recurrence

Recurrence is the most important postoperative complication.

It usually occurs within:

The first 6–12 months

although later recurrence can occur.

Risk Factors for Recurrence

Higher recurrence risk is associated with:

• Younger age
• Fleshy/vascular pterygium
• Large lesion
• Recurrent pterygium
• Persistent postoperative inflammation
• High UV exposure
• Bare sclera technique
• Inadequate fibrovascular tissue removal

Recurrent Pterygium

Recurrent lesions may be:

• More vascular
• More fibrotic
• More adherent
• More difficult to remove

They may cause:

• Restrictive strabismus
• Significant corneal scarring
• Symblepharon

Management often requires:

• Extensive scar dissection
• Conjunctival-limbal autograft
• MMC
• Amniotic membrane in selected cases

Postoperative Complications

Potential complications include:

• Recurrence
• Graft edema
• Graft displacement
• Granuloma
• Dellen formation
• Infection
• Diplopia
• Scleral thinning
• Corneal scar
• Persistent epithelial defect
• Rare scleral melt

Dellen

A corneal dellen is localized peripheral corneal thinning caused by:

• Tear-film instability
• Adjacent elevation

It may occur near:

• Pterygium
• Postoperative graft elevation

Treatment includes:

• Aggressive lubrication
• Reduction of adjacent inflammation/elevation

Follow-Up

Small stable lesions can generally be followed:

• Periodically
• Often annually

Earlier review is appropriate if there is:

• Documented progression
• Increasing astigmatism
• Increasing symptoms
• Suspicious morphology

Postoperative Follow-Up

Monitor for:

• Epithelial healing
• Graft position
• Infection
• IOP elevation from steroids
• Recurrence

Long-term UV protection should be encouraged.

Prognosis

Prognosis is generally:

Excellent

when lesions are small and managed appropriately.

After surgery, visual improvement may result from:

• Reduced astigmatism
• Improved corneal regularity

However, longstanding central lesions may leave:

• Persistent corneal scar
• Residual irregular astigmatism

Ophthalmology Pearls

• Pterygium is a benign fibrovascular conjunctival growth that crosses the limbus onto the cornea, usually nasally.
• The strongest environmental risk factor is chronic UV exposure, especially in tropical climates and outdoor workers.
• Modern understanding views pterygium as an active UV-related proliferative and inflammatory process, not merely passive degeneration.
• Visual impairment can occur from induced astigmatism well before the lesion reaches the visual axis.
• Stocker line is iron deposition just anterior to the pterygium head and does not reliably prove inactivity.
• A pinguecula does not cross the limbus; a pterygium does.
• A pseudopterygium follows trauma or inflammation and can occur at any limbal location.
• Atypical, leukoplakic, nodular, rapidly growing, or temporal lesions should raise concern for OSSN and may require biopsy.
• Lubricants and short courses of topical steroids can relieve symptoms but do not eliminate the pterygium.
• Surgery is indicated for progression, visually significant astigmatism, threatened visual axis, persistent symptoms, motility restriction, or significant cosmetic concern.
• Conjunctival autograft is the preferred technique for most primary pterygia because of its low recurrence rate.
• The bare sclera technique should generally be avoided because recurrence is high.
• MMC reduces recurrence but must be used judiciously because of potentially serious complications such as scleral melt.
• Amniotic membrane is useful when conjunctiva needs to be preserved, but for routine primary pterygium surgery it generally has a higher recurrence rate than conjunctival autograft.
• Recurrence occurs most commonly during the first postoperative year.
• A fixed 6-month steroid course is not required for every patient; postoperative anti-inflammatory therapy should be individualized.
• Continued UV-blocking eyewear and hats are important after surgery to reduce ongoing environmental exposure.