Description, symptoms, prevalence, significance, differential diagnosis
See Acute angle-closure glaucoma – assessment.
Urgent Immediate treatment is required, as angle-closure glaucoma (ACG) has the potential for total visual loss from optic nerve damage within 24-36 hours. Initial therapy aims to lower intraocular pressure (IOP) as quickly as possible, to open the angle and ameliorate corneal edema.
Topical medication Topical antiglaucoma medications should be instilled immediately, for example apraclonidine 0.5 per cent, timolol 0.5 per cent and/or dorzolamide 2 per cent. The patient’s general health status will determine the combination to be used. Latanoprost should be avoided owing to the latency of its action and potential to cause intraocular inflammation. Once therapy has been started, IOP should be checked every 15-30 min. A topical steroid (e.g. prednisolone acetate 1 per cent every 15 min for four times and then every hour) may be prescribed if significant inflammation is present. Pilocarpine 2 per cent may also be used. One drop should be instilled every 15 min for 1 hour (four doses). Pilocarpine should also be instilled in the other eye to prevent the development of pupil block, and continued in the fellow eye two to four times per day until laser iridotomy has been performed. However, if the attack lasts for more than 1-2 hours, or if IOP is above 50 mmHg, the iris sphincter muscle is likely to be ischemic and therefore unresponsive to pilocarpine. Caution needs to be exercised with pilocarpine if risk factors for retinal detachment are present, and prolonged use of pilocarpine may lead to general cholinergic symptoms.
Oral and intravenous medication This is indicated if IOP is over 50 mmHg or visual loss is significant. Established pupil block is initially treated with oral or intravenous acetazolamide, usually 500 mg stat, to reduce aqueous production. Hyperosmotis.agents such as oral glycerin or intravenous mannitol may be used to reduce vitreous volume if acetazolamide is insufficient. Medications for pain or vomiting may be required.
Laser treatment The definitive treatment for pupil-block ACG is with Nd: YAG (neodymium: yttrium-aluminium-garnet) laser peripheral iridotomy (LPI). Corneal edema may need to be cleared with topical hyperosmotic agent (glycerin), if LPI is required acutely to lower the IOP. Treat the contralateral eye within a few days to protect it from a similar attack. Argon laser peripheral iridoplasty (ALPI) involves the placement of a ring of contraction burns on the peripheral iris to contract the iris tissue near the drainage angle. ALPI has been advocated by the Chinese University of hlong Kong as effective in promptly relieving the signs and symptoms of acute primary angle-closure glaucoma without use of systemic antiglaucoma medications
Incisional surgery Other surgical treatments advocated in recent years for acute and chronic ACG include ,ij ^ paracentesis and cataract extraction. Anterior chamber paracentesis produces an immediate reduction in IOP and symptomatic relief, and has been advocated in conjunction with medical therapy. Both paracentesis and ALPI are usually followed by LPI. If LPI is ineffective, surgical iridectomy or trabeculectomy may be indicated. Cataract extraction is also an effective measure to prevent the development of pupil block in the other eye.
Anterior photo of acute angle closure, with fixed pupil and cloudy cornea. Courtesy of Anthony Chapman-Davies, Sydney
Slitlamp photo of shallow anterior chamber (<2mm depth) associated with brunescent nuclear cataract. Note the relatively narrow separation between the light beams on the cornea and lens, in relation to the corneal beam width
Review Once the IOP and any intraocular inflammation are under control, the patient’s visual field is usually assessed
with static perimetry. The IOP is reassessed at follow-up, several weeks after treatment.