Primary Angle Closure Glaucoma is a condition in which elevation of intraocular pressure (IOP) occurs as a result of obstruction of aqueous outflow by partial or complete closure of angle by the peripheral iris.
I. Classical Classification:
- Prodromal Stage
- Stage of constant instability
- Acute Congestive Stage
- Chronic Angle Closure Stage
- Absolute Stage
II. Newer Classification:
Recommended by the American Academy of Ophthalmology (AAO) and World Glaucoma Association (WGA).
1. Primary Angle Closure Suspect
This includes any eye that has a primary, abnormally narrow angular width of the anterior-chamber-angle recess, wherein the peripheral iris is located close to, yet not touching, the posterior pigmented trabecular meshwork. Patients with primary anatomic narrow anterior-chamber angles are at risk for subsequent primary angle closure (PAC).
2. Primary Angle Closure and Primary Angle-Closure Glaucoma
Any eye that has a primary anatomic narrow anterior-chamber angle and evidence such as peripheral anterior synechiae (PAS), elevated IOP, sector iris atrophy, or glaukomflecken lens opacities, when trabecular obstruction by the peripheral iris has occurred is classified as having PAC. This entity is caused by pupillary block and can exist in an acute state or a chronic state. The fellow eye is at risk. Patients with PAC can present with either the acute or chronic state or they may have both and present with acute attacks superimposed on chronic angle closure. In PAC the eye is at risk of developing glaucomatous optic disc damage, particularly when associated with elevated IOP. In this case the eye has progressed from PAC to primary angle closure glaucoma (PACG).
A. Acute Primary Angle Closure:
If the entire circumference of the chamber angle is obstructed suddenly, the IOP will rise rapidly to high levels. This may cause pressure-induced corneal edema (experienced as blurred vision and occasionally as multicolored halos around lights) vascular congestion, eye pain, or headache. High IOP may be accompanied by nausea and vomiting. Acute attacks may be self-limited and resolve spontaneously or may occur repeatedly. Untreated, this entity may cause permanent vision loss or blindness.
B. Chronic Primary Angle Closure:
If only a portion of the angle closes with PAS, either slowly over time with or without acute attacks, or rapidly after a resolved acute attack of angle closure, the IOP may be in the normal range or only mildly elevated, and symptoms of acute PAC may be mild or absent. Continued, slowly progressive closure of the angle may ensue, eventually leading to sustained elevation of IOP and glaucomatous optic neuropathy. By nature of its chronicity and the insidious increase in IOP, chronic PAC my not have any of the findings of acute angle closure and can be mistaken for primary open angle glaucoma. Patients with asymptomatic chronic PAC may present with severe visual field loss compared with the mild to moderate defects found in patients with prior episodes of symptomatic angle closure.
3. Plateau Iris Configuration and Plateau IrisSyndrome
The definitions of these entities are included here because they are primary conditions that are often difficult to distinguish from the PAC entities resulting from pupillary block.
Plateau iris configurationis characterized by a near-normal-depth central anterior chamber, a flat iris profile, and crowding of the anterior chamber angle by the iris base. The IOP may be normal or elevated. The condition appears to be related to a forward displacement of the ciliary processes that causes anterior displacement of the peripheral iris and angle closure. Such closure occurs without a significant pupillary block component.
Plateau iris syndromeis defined as having a plateau iris configuration with a closed anterior chamber angle and usually with elevated IOP, which persists despite the elimination of any pupillary block component by a patent iridotomy. Intraocular pressure elevation that was present before iridotomy may persist; the IOP typically increases after pupil dilatation, which causes greater occlusion of the angle by the peripheral iris.
2. Family history of glaucoma
3. Advancing age
4. Female gender
5. Asian descent
6. Shallow peripheral anterior chamber
If patients with unilateral acute PAC with high IOP do not receive treatment, glaucomatous optic neuropathy can occur rapidly (within days) or gradually (over years). Untreated fellow phakic eyes are at increased risk for developing acute angle closure. Following successful treatment of acute PAC, there is evidence that retinal nerve fiber layer thickness significantly decreases within 16 weeks after the attack. In one study, in the long term (4 to 10 years) following an acute PAC attack, 18% of eyes were blind, 48% of eyes developed serious glaucomatous optic neuropathy, and 58% of eyes had vision worse than 20/40. Thus, visual morbidity from the acute and chronic effects of angle closure may be significant. The natural history of acute and chronic angle-closure glaucoma is for the untreated patient to develop progressive visual loss that may result in bilateral blindness.
Theories of Mechanism:
Relative Pupillary Block:
The most common mechanism leading to angle closure glaucoma appears to be the increased resistance to aqueous flow from posterior to anterior chamber. The resultant pressure gradient between the posterior and anterior chamber causes a forward bowing of the peripheral iris so that the iris covers all (or) part of the filtering portion of trabecular meshwork (appositional angle closure).
Prolonged (or) repeated contact of peripheral iris with the trabecular meshwork (TBM) may lead to PAS and residual damage to TBM.
Patients with PAC may present for care in different ways. Patients being examined in another context may be noted to have a shallow anterior-chamber angle with normal IOP. Patients may present for care who have been found to have elevated IOP or optic disc cupping and whose slit lamp biomicroscopy suggests a shallow anterior chamber that is confirmed by gonioscopy and patients may present with sudden onset of symptoms typical of PAC (such as pain, redness, congestion, corneal edema, very high IOP). The initial history and physical examination includes evaluation for both primary and secondary types of angle closure. This includes the appropriate components of the comprehensive adult medical eye evaluation, with particular attention to those aspects relevant to the various types of angle closure.
- History of using topical and systemic medications that may induce angle closure.
- e.g., Sulfonamides, Topiramate, Phenothiazines
- Symptoms that suggest intermittent angle closure
- e.g., blurred vision, haloes around lights, aching eye or brow pain, eye redness
If acute angle closure is present, some components of the examination may be postponed. Components of the physical evaluation that are particularly relevant for the diagnosis and management of angle-closure include the following.
Assessment of refractive status:
It is important to assess refractive status, since hyperopic eyes, especially in older patients have narrower anterior chamber angles and is at increase risk of PAC.
- Conjunctival hyperemia
- Corneal clarity
- Central and peripheral anterior chamber depth
- Anterior-chamber inflammation suggestive of a recent or current attack
- Corneal edema
- Iris atrophy, especially sector types; posterior synechiae; or mid-dilated pupil suggestive of a recent or current attack
- Signs of previous angle-closure attacks (e.g.,PAS, segmental iris atrophy, glaukomflecken, posterior synechiae, pupillary dysfunction, irregular pupil)
Determination of IOP:
Intraocular pressure is measured in each eye, preferably using a contact applanation method (typically a Goldmann tonometer) before gonioscopy. Measuring central corneal thickness should be postponed until the resolution of an acute attack.
Gonioscopy of both eyes should be performed on all patients in whom angle closure is suspected. This is required to evaluate the angle anatomy, appositional closure, and presence of PAS. Compression (indentation) gonioscopy with a four-mirror or similar lens is particularly helpful to evaluate for appositional closure versus synechial angle closure and for extent of PAS.
It is proposed to predict which patients will develop angle-closure glaucoma. It produces a mild episode of angle-closure under our observation. It’s not likely to cause permanent damage. However history, clinically examination and gonioscopy are more reliable.
E.g. Darkroom test of seidel
Prone provocative test
Pilocarpine Phenylepherine test
All these tests are usually performed after baseline measurement of IOP and gonioscopy.
Other components of the initial evaluation
Although a dilated examination may not be advisable in patients with anatomic narrow angles or angle closure, an attempt should be made to evaluate the fundus and optic nerve using the direct ophthalmoscope or biomicroscopy. For patients with PAC or narrow-angle who are not in an acute attack, pupil dilation is contraindicated until iridotomies have been performed. Evaluation and documentation of the optic nerve head, retinal nerve fiber layer, and visual fields may be postponed until an acute attack is adequately treated.
Because primary narrow angles and PAC tend to be bilateral, the observation of a wide-open angle in the fellow eye suggests a diagnosis other than PAC. The differential diagnosis of PAC includes the following entities, which cause a secondary anterior-chamber angle closure and which may be unilateral or bilateral.
- Neovascular glaucoma
- Inflammatory causes of angle closure (e.g. posterior synechiae, iris bombe)
- Iridocorneal endothelial syndrome
- Ciliary body engorgement or suprachoroidal effusion caused by systemic medications (e.g. Topiramate, Sulfonamides, Phenothiazines)
- Ciliary body engorgement associated with retinal vascular occlusion or scatter (Pan retinal) photocoagulation.
- Anterior suprachoroidal effusions (e.g. congestion, edema, displacement)
- Aqueous misdirection (ciliary block) syndrome after incisional or laser surgery (e.g. following peripheral iridectomy)
- Lens-induced angle closure (e.g. Phacomorphic or subluxed)
- Developmental disorders (e.g. nanophthalmos, retinopathy of prematurity , persistent hyoperplastic primary vitreous)
- Iris or ciliary body mass lesions or cysts
- Other secondary causes of pupillary block (e.g., aphakia without an iridectomy, vitreous block, silicon oil)
- Reverse or prevent angle-closure process
- Control IOP elevation
- Inhibit damage to the optic nerve
Primary Angle Closure Suspect
In patients with narrow angles, iridotomy should be considered in eyes regarded as at risk for developing angle closure. Patients with narrow but open angles should be followed for development of IOP elevation, evidence of progressive narrowing or development of synechial angle closure. Although there is no evidence that iridotomy is indicated for the presence of narrow but open angles with normal IOP, the availability of laser iridotomy and its relative safety compared with incisional iridectomy has improved the risk-benefit ratio and has allowed treatment to prevent angle closure as well as its potential vision-threatening sequelae. Laser iridotomy may be considered for patients with narrow angles who require repeated pupil dilation for treatment of other eye disorder.
Iridotomy may be indicated for eyes with narrow angles under one or more of the following additional circumstances:
- Previously normal IOP is elevated
- A potentially occludable angle is present
- PAD that are attributable to episodes of angle closure are present
- There is progressive narrowing of the angle
- Medication is required that may provoke pupillary block
- Symptoms are present that suggest prior angle closure
- The patient's occupation / avocation make it difficult to access immediate ophthalmic care (e.g. the patient travels frequently to developing parts of the world or works on a merchant vessel).
- For the fellow eye in patients who have had an attack of acute PAC (as described in the section about "acute primary angle closure" under orientation).
Patients at risk for angle closure should be warned of the danger of taking medicines (e.g. over the counter decongestants, motion sickness medication, anticholinergic agents) that could cause pupil dilation and induce an angle closure attack. They should also be informed about the symptoms of acute angle closure attacks and instructed to notify their ophthalmologist immediately if symptoms occur.
Cataract surgery with a posterior chamber intraocular lens implant in eyes with an anatomically narrow angle results in a wider angle and may decrease the risk of pupillary block.
Treatment of Acute Primary Angle Closure
Management of acute congestive glaucoma is done in 4 stages:
- Immediate medical therapy to stop the attack
- there by reducing the formation of PAS and PS
- minimizing the damage to optic nerve, TBM, lens
- Protection of the fellow eye
- Definitive treatment Iridotomy in both the involved eye and fellow eye
- Management of sequalae of angle closure attack
In acute angle-closure attacks, medical therapy is usually initiated first to lower the IOP, to reduce pain and clear corneal edema in preparation for iridotomy. Medical therapy includes some or all of the following, based on the patient's overall physical and medical status.
- Topical beta-adrenergic antagonists
- Topical alpha-adrenergic agonists
- Topical or systemic carbonic anhydrase inhibitors
- Topical miotics
- Systemic hyperosmotic agents
Agents that suppress aqueous humor formation (beta-adrenergic antagonists, carbonic anhydrase inhibitors) may be ineffective because they will have decreased ability to reduce aqueous formation if the ciliary body is ischemic. As the configuration of the iris becomes less bowed with a small pupil, treatment with miotics may open the angle; this effect may be enhanced by a lower IOP. Corneal indentation performed with a four-mirror gonioscopic lens, cotton-tipped applicator, or tip of muscle hook may help break pupillary block.
Laser iridotomy is the preferred surgical treatment because it has a favorable risk-benefit ratio. The iridotomy reverses appositional angle closure, and it prevents or retards formation of PAS. Timely treatment may prevent damage to the optic nerve, trabecular mesh work, iris, lens and cornea. If an iridotomy cannot be performed due to corneal edema, the cornea may sometimes be cleared with topical hyperosmolar agents or anterior chamber paracentesis using a 30 gauge needle. Argon laser peripheral iridoplasty may temporarily open the angle enough to break the acute attack. This usually allows the inflammation to subside and corneal edema to clear sufficiently to perform a definitive laser iridotomy immediately or several days later.
When laser iridotomy is not possible or if the acute angle closure attack cannot be medically, broken, incisional iridectomy remains an effective alternative. When incisional iridectomy is required and extensive synechial closure is recognized or suspected, primary filtering surgery may be considered. Concurrent glaucomatous cupping of the optic disc often indicates a prolonged chronic course before the onset of acute symptoms and may indicate that filtering surgery is an appropriate choice, especially if the presence of considerable PAS is confirmed gonioscopically. There is a higher risk of these patients with narrow anterior chamber angles developing a flat anterior chamber and aqueous misdirection postoperatively. Patients who require bilateral incisional iridectomy should have surgery on one eye at a time (several days apart) whenever feasible to avoid simultaneous bilateral complications.
The fellow eye of a patient with an attack of acute PAC should be evaluated since it is at high risk for a similar event. The fellow eye should receive a prophylactic iridotomy if the chamber angle is anatomically narrow, since approximately half of fellow eye or for treatment of established angle closure, and it is not a substitute for iridotomy. Thirty-nine percent of fellow eyes treated with miotics will suffer an acute attack within 5 years, and many eyes with angle-closure suffer progressive formation of synechial angle closure with miotic use. Prophylactic laser peripheral iridotomies are effective in preventing acute angle closure in the fellow eye.
Treatment of Chronic Primary Angle Closure
Patients with chronic PAC may have elevated IOP as a result of a chronic compromise of aqueous outflow through appositional or synechial angle closure, or damage to the trabecular meshwork from the acute angle closure. In such patients, synechial angle closure usually starts superiorly in the narrowest part of the angle and may progress circumferentially. Miotics may aggravate pupillary block due to anterior rotation of the ciliary body and, when used chronically, may increase the risk of synechial angle closure, especially if cataract formation increases lens-iris contact. Peripheral iridotomy is performed to relieve the pupillary block component and this usually halts the progression of synechial closure and progressive IOP elevation.
Following iridotomy for PAC, persistent or progressive elevations of IOP and complications may occur for several reasons:
Trabecular damage or formation of synechiae may have occurred during iridocorneal apposition.
If the iridotomy becomes occluded, pupillary block may recur, reoperation is indicated.
Factors other than pupillary block may lead to angle closure and may have gone unrecognized until after the iridotomy. These include plateau iris syndrome and secondary causes of pupillary block (please see differential diagnosis section)
Angle closure may have been superimposed on pre-existing open angle glaucoma or on other causes of IOP elevation, such as pseudoexfoliation.
There may be co-existing chronic open-angle glaucoma.
Treatment of chronic PAC after the component of pupillary block has been alleviated is directed at lowering IOP to prevent or retard pressure-induced optic nerve damage and is similar to the treatment of primary open angle glaucoma. Reopening the angle by laser iridoplasty or surgical lysis of synechiae (goniosynechialysis) may improve outflow, especially when it is performed within 6 to 12 months of an acute attack.
Numerous studies document the widely held clinical impression that lensectomy significantly widens the anterior-chamber angles in eyes with narrow/occludable angles and in angle-closure glaucoma, except in plateau iris syndrome. In retrospective studies, cataract surgery also has been shown to lower postoperative medication requirements and decrease complications compared with surgical iridectomy or trabeculectomy in angle closure glaucoma. While there is currently insufficient evidence to recommend the use of cataract surgery in the management of PAC it can be considered with or without goniosynechialysis.
Safe, effective technique preferred alternative to surgical iridectomy
- Topical anesthesia
- Pupil constricted with 2% Pilocarpine
- 1% Apraclonidine to be applied to reduce post laser IOP spike
Antireflective coated lens such as Abraham lens (+66 D) (or) Weiss lens (+103 D) can be used. Iris crypt between 11 and 1 o'clock is selected. About 5-15 mj energy can be used. Iridotomy of size 150-200 µm will suffice. Patient need to be treated with topical steroids for a week (or) two after the procedure.
a. Aphakic (or) psuedophakic pupillary block
b. Malignant glaucoma
d. Pigment dispersion syndrome
e. To penetrate nonfunctional surgical PI
f. Combined mechanism glaucoma
Blurred vision, pupillary abnormalities, diplopia, corneal damage, anterior uveitis, posterior synechiae, haemorrhage, elevation of IOP, lens opacity, zonular damage, retinal damage.
The patient should be followed up on first day, first week and first month after laser PI. During each follow up visit vision and IOP should be estimated and gonioscopy should be done to assess the angle.
1. Shield's Test Book of Glaucoma
2. Becker Shaffer's – Diagnosis and Therapy of the Glaucomas
3. Preferred Practice Pattern – American Academy of Ophthalmology