Chronic Angle Closure Glaucoma

Chronic angle closure glaucoma is progressive, often asymptomatic closure of the anterior chamber angle by permanent peripheral anterior synechiae (PAS), with raised pressure and glaucomatous optic neuropathy.

• Develops from repeated subacute attacks, residual angle closure after acute attack, or gradual creeping closure from the angle periphery inward, with a narrow angle and intermittent or slow closure.
• Predominant in East and South Asian populations; accounts for the majority of angle closure glaucoma cases.
• Mechanisms: pupil block, plateau iris, thick lens, and trabecular meshwork damage from chronic contact.

• Usually silent: no pain, progressive loss of peripheral field, similar to open angle disease, discovered late with advanced cupping.
• Raised pressure (often 25 to 40 mmHg), shallow chamber, narrow angle, PAS visible on gonioscopy (often superior, appearing as tent like adhesions), and trabecular pigmentation.
• Disc cupping and field loss disproportionate to the pressure measurement.
• Occasional subacute symptoms (haloes, mild ache) and glaukomflecken.

• Gonioscopy (with indentation) to identify extent of PAS; angle appositional versus synechial closure.
• Ultrasound biomicroscopy or anterior segment OCT; assess for plateau iris with ultrasound biomicroscopy (anteriorly positioned ciliary processes, flat iris plane, and persistent angle closure after a patent iridotomy).
• Tonometry, disc examination, OCT, perimetry, and baseline for monitoring.
• Axial length and lens thickness to plan surgical strategy.

• Laser peripheral iridotomy to relieve any pupil block (Nd:YAG 3 to 8 mJ), followed by peripheral iridoplasty for plateau iris with appositional closure.
• Medical therapy for residual pressure elevation: prostaglandin analogue at night, timolol 0.5 percent, dorzolamide 2 percent, brimonidine 0.2 percent. Avoid chronic miotic use as a primary agent.
• Lens extraction (phacoemulsification) with or without goniosynechialysis and endocyclophotocoagulation: often effective as first or second step, deepening the chamber and lowering pressure by about 4 to 8 mmHg.
• Surgery for uncontrolled pressure or advanced disease: trabeculectomy with mitomycin C 0.2 to 0.4 mg/mL (higher risk of malignant glaucoma and need for cycloplegic prophylaxis), combined phacotrabeculectomy, drainage devices (Ahmed, Baerveldt), and cyclodestructive procedures (transscleral cyclophotocoagulation, endoscopic cyclophotocoagulation) for refractory cases.
• Malignant glaucoma risk after filtering surgery in short eyes: atropine 1 percent postoperatively.
• Lifelong follow up with pressure, discs, fields and OCT every 3 to 6 months.
• Screen family members, as angle closure has a heritable anatomical basis.