​Kembara Xtra - Medicine - Primary Closed Angle Glaucoma

​Kembara Xtra - Medicine - Primary Closed Angle Glaucoma 
Glaucoma, which causes progressive vision loss due to damage to the optic nerve, is frequently accompanied with increased intraocular pressure (IOP) in the eye. The trabecular meshwork (TM) is mechanically blocked by angle-closure, which is caused by the peripheral iris.
There is an anatomic tendency for primary angle-closure (PAC), but no discernible secondary pathologic disease.
There is a pathologic reason for secondary angle-closure, such as iris neovascularization or an enlarged cataractous lens.
● Angle-closure falls within one of the following categories:
- There is >180 degrees of iridotrabecular contact (ITC) as the primary angle-closure suspect (PACS), but there is no sign of TM or optic nerve injury.
- PAC is >180 degrees of ITC without ocular neuropathy, increased IOP, or peripheral anterior synechiae (PAS).
- Primary angle-closure glaucoma, also known as glaucomatous optic neuropathy, is a form of PAC.
Acute angleclosure crisis (AACC) or acute primary angle-closure (APAC) occurs when the angle is blocked by symptomatic high IOP. It is a medical emergency that has to be treated right away.
After APAC, chronic angle closure (CAC), in which synechial closure persists, may form. It can also happen when the angle slowly closes and the function of the angle steadily deteriorates, causing a steady increase in IOP. Given that the illness is asymptomatic, vision loss may be the presenting complaint.

Aspects of Geriatrics
age-related risk factors and cataracts

pregnant women's issues

Utilized medications could pass the placenta and end up in breast milk. The majority of IOP-lowering drugs fall under class C, thus it is important to weigh the mother's risk of vision loss against the fetus's risk of severe consequences.

epidemiology, senior citizens, and female sex. Women are 2–4 times more likely than men to have PAC. Women typically have shorter axial lengths and smaller anterior portions.
More prevalent in Inuit and people of East or South Asian ancestry

Prevalence
Depending on race and ethnicity, PACG is more common in people over 40. The prevalence is 0.1%- 0.2% for black people, 0.1%-0.6% for white people, 0.3% for Japanese people, 0.4%-1.4% for other East Asian people, and 2.1%-5.0% for Inuit people. In Asian nations, PACG is more of a hardship.

Pathophysiology and Etiology 

When the iris meets the TM in the anterior chamber angle, PAC occurs. ITC results in aqueous humor outflow through the TM being blocked, which raises IOP.
Long-term ITC can result in PAS development and scarring.
Angle closure is most frequently caused by pupillary occlusion of the aqueous passage from the posterior to anterior chamber. As a result, the posterior chamber experiences greater pressure than the anterior chamber.
The iris bows anteriorly as the angle closes as a result of pressure accumulation in the posterior chamber. The dilatation of the pupil is one of the most crucial elements in an anatomically predisposed eye's angle closure process.
Darkness, emotion, and drugs that might cause the pupil to dilate are just a few of the factors that can cause dilation leading to angle closure. When the pupil is mid-dilated, the amount of pupillary block is at its greatest.
An abnormal anterior chamber angle configuration known as plateau iris syndrome can cause either acute or chronic PAC. The anteriorly positioned ciliary processes that narrow the anterior chamber recess by forcing the peripheral iris forward are most frequently responsible for angle-closure in plateau iris. There is frequently a pupillary block component.

Genetics

First-degree relatives increase risk by 1–12% in whites, and by 6–times in Chinese patients with a positive family history.


Age over 50, female gender, Asian or Inuit ancestry, family history of angle closure, shallow anterior chamber, hyperopia, short axial length, thick crystalline lens, anteriorly positioned lens, and plateau iris are risk factors.
Adrenergic agonists (albuterol, phenylephrine), anticholinergics (oxybutynin, atropine), antihistamines, antidepressants, including selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs), and cocaine are some medications that can cause angle closure by dilation of the pupil. Topiramate and other sulfonamides are medications that can cause


Prevention 

For high-risk individuals, routine eye exams should include gonioscopy. In PACS patients, prophylactic laser peripheral iridotomy (LPI) may be explored to prevent PACG.

 For patients with plateau iris syndrome, argon laser peripheral iridoplasty


Related Disorders Cataract and Hyperopia

Patient may be asymptomatic as in PACS or may have acute symptoms as in APAC, according to the diagnosis.

 Unilateral: are frequently present in acute symptoms.
- Profound eye ache - Vision haze
Red eyes, haloes around lights and objects, and a headache
- Vomiting and dizziness
Patients with PACG can have subacute symptoms (intermittent subacute episodes), be asymptomatic, or have impaired peripheral vision.
Obtain a history of prescription, over-the-counter, and herbal drugs. Obtain a family history of acute angle-closure glaucoma.


clinical assessment 

contains the following in the undilated eye, but not only:
Visual acuity with refractive error (particularly in older phakic patients with hyperopic eyes)
Visual field evaluation
The size and reactivity of the pupils (mid-dilated, oval or asymmetric, mildly reactive, and possibly with a relative afferent pupillary deficiency)
Conjunctival hyperemia (in acute cases), central and peripheral anterior chamber shallowing, corneal edema, iris abnormalities (diffuse and focal iris atrophy, posterior synechiae), and lens alterations (cataract and glaukomfleckenpatchy localized anterior subcapsular lens opacities) are all visible during a slit-lamp examination.
elevation of IOP. IOP levels during an acute attack may be high enough to result in retinal vascular occlusion, glaucomatous optic nerve injury, and/or ischemic nerve damage.
The Van Herick assessment (VHA), which compares the peripheral anterior chamber depth to the peripheral corneal thickness using a small slit lamp beam of light, is a noncontact estimation of the angle configuration.
VHA misses a significant percentage of angle closure, even when done by skilled ophthalmologists.
Gonioscopy enables visualization of the anatomy of both eyes' angles. Find ITC and PAS.
Understanding the anatomy of the angle using anterior segment imaging with ultrasound (US), biomicroscopy, and anterior segment optical coherence tomography (AS-OCT)

Multiple Diagnoses 
The iris membranes cause secondary angle closure.
- Iridocorneal endothelial (ICE) syndrome - Neovascularization of the iris
Secondary pupillary obstruction as a result of:
- Iris bombe caused by secondary posterior synechiae and uveitis
- Conditions affecting the retina that cause the lensiris diaphragm to shift forward, such as uveal effusion, hemorrhagic choroidal separation, and intraocular tumors. - Lens-related disorders, such as ectopia lentis or malpositioned intraocular lenses.
● Oral topiramate is a medicine used to treat headaches, depression, and epilepsy. This medicine may lead to a condition in some people that includes abrupt bilateral angle closure and acute myopic shift. The medicine must be stopped right afterwards, and medical therapy to decrease IOP must be started. The anterior chamber may deepen with cycloplegia, which would then stop the onslaught. An LPI is not recommended because pupillary obstruction is not the syndrome's underlying cause.
A uncommon type of glaucoma called malignant glaucoma, also known as aqueous misdirection, typically manifests after eye surgery. Use of miotics can exacerbate malignant glaucoma; cycloplegics are preferred.

Laboratory Results 

Gonioscopy, US biomicroscopy, AS-OCT Test Interpretation, Initial Tests (Lab, Imaging),
anterior chamber angle that is small or closed

Administration Caution 
Consult an ophthalmologist right once if a patient has acute symptoms (severe eye pain, blurred vision, eye redness, haloes around lights or objects, headache, nausea, or vomiting).


General Actions 

Angle-closure process reversal or prevention, IOP management, and protection of the optic nerve are the objectives of treatment.

Medication: During an acute episode, medicinal therapy reduces IOP to ease symptoms and eliminate corneal edema, allowing for the earliest feasible LPI.
Medical treatment attempts to:
- Reduction in the generation of aqueous:
Acetazolamide, a carbonic anhydrase inhibitor (CAI), is available as a 250 mg tablet or an IV dose of up to 500 mg.
CAI for the skin, such as 2% dorzolamide. Sulfa allergy and hepatic impairment are contraindications to using CAIs.
Topical beta-blockers, like timolol 0.5%. In individuals with lung illness, use with caution.
 Topical 2-agonists like brimonidine (0.2%).
- Latanoprost 0.005% and other prostaglandin analogues improve uveoscleral outflow and raise aqueous outflow.
Topical pilocarpine 1% or 2% q15min causes pupillary constriction, which opens the chamber angle. When IOP is noticeably increased as a result of iris sphincter ischemia, miotic treatment may be unsuccessful.
- Prednisolone acetate 1% q15–30min–4 and then hourly as a topical steroid to treat the inflammation
- Hyperosmotic substances that lower vitreous volume and consequently IOP
1.0 to 1.5 g/kg of a 50% glycerin solution is given orally. If the patient is vomiting or feeling sick, use with caution. The solution can be poured over crushed ice after being diluted with a tiny bit of orange juice to enhance the flavor.
 Mannitol 20% solution, given IV over 30 to 60 minutes at 1.5 to 2.0 g/kg of body weight.
When treating individuals with heart and kidney conditions, hyperosmotic agents should be utilized carefully. Because it can raise blood sugar levels, glycerin should not be administered to diabetic individuals. Acetazolamide 500 mg IV is used during an acute episode, followed by 500 mg PO BID. 0.5% timolol maleate and 0.2% brimonidine drops, spaced 1 minute apart, are used to start topical therapy. Frequently applying topical steroids helps to reduce inflammation. Additionally, systemic therapy using oral glycerol (Osmoglyn) (50%) 6 oz PO or mannitol 20% 1.5 to 2.0 g/kg injected over 30 to 60 minutes may be required. Use analgesics and antiemetics to treat pain and nausea. Start the course of treatment with 3 doses of 1% or 2% pilocarpine drops given 15 minutes apart in an effort to open the angle.


Surgical Techniques 
The only treatments left are argon LPI or Nd:YAG for PAC, PACG, and AACC. LPI can be carried out superiorly or temporally.
The location of the LPI does not appear to have an impact on the development of fresh postoperative dysphotopsies.
If laser iridotomy cannot be done because the cornea is clouded, surgical iridectomy may be done.
If a cataract is present, LPI or lensectomy may be used as the initial treatment for plateau iris syndrome. Despite a patent iridotomy or lensectomy, eyes with plateau iris syndrome continue to be prone to angle closure. To shrink and flatten the peripheral iris, argon laser peripheral iridoplasty can be required. There is mounting evidence that cataract removal by itself can lower IOP and lower the chance of lens-induced angle closure. In the right circumstances, this can be taken into account as a therapy option. - APAC patients who underwent phacoemulsification with an intraocular lens (IOL) had better IOP control, deeper anterior chambers, and required fewer glaucoma medications than those who underwent LPI alone. Additional procedures to lower IOP include argon laser peripheral iridoplasty (especially for plateau iris syndrome), anterior chamber paracentesis, goniosynechialysis, and trabeculectomy.
- Clear lens extraction (CLE) can be considered for firstline treatment of eyes with more advanced angleclosure disease, such as APAC eyes with an IOP >30 mmHg. - Phacoemulsification performed weeks to months after the initial LPI did not appear to have a negative impact on outcomes compared to early phacoemulsification.
CONTINUING CARE AFTERCARE RECOMMENDATIONS
patient observation
Within five years, APAC will develop in 50% of the patient's other eye. Therefore, preventive LPI should be carried out as soon as possible in the other eye.

Encourage the patient to get immediate help if they notice a change in their eyesight, blurred vision, eye pain, or a headache.
Avoid using decongestants, motion sickness remedies, adrenergic drugs, antipsychotics, antidepressants, and anticholinergic agents; PACS patients without LPI.

The prognosis is based on ethnicity, the underlying eye condition, and the length of time till therapy.
Most PACS subjects should not require further therapy after LPI.
After LPI, many PAC and APAC eyes as well as the majority of PACG eyes have further treatment to reduce IOP.

Complications include: malignant glaucoma; chronic angle closure; iris atrophy; cataract; optic atrophy; central retinal artery/vein obstruction; a permanent loss of vision; blindness; and a fellow (contralateral) eye attack.

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