Treatment

Acute narrow-angle glaucoma is a surgical problem and any patient suffering from the condition requires urgent admission to hospital. To do less than this is to undertreat the condition and run the risk of producing chronic narrowangle glaucoma. On admission, the affected eye is treated with intensive miotic drops. A typical regimen would be the application of pilocarpine 4% every minute for 5min, then every 5min for an hour, followed by instillation every hour. This treatment is supported by an injection of acetazolamide. If the renal function is unimpaired, acetazolamide can be given intravenously (usually 500 mg) followed by an oral dose of 250 mg four times a day. Topical beta-blockers and/or alpha-agonists, for example apraclonidine (Iopidine), and reduction of inflammation and iris congestion by topical steroids can help achieve a quicker lowering of intraocular pressure. In many cases, these measures relieve the acute attack within hours. However, some patients can require an intravenous infusion of mannitol. During this period, the patient is kept in bed and analgesics are given if required. It is important that the other eye is also treated with pilocarpine 2% four times a day in order to prevent a second disaster.

Once the intraocular pressure has been controlled, the cure is maintained by performing a peripheral iridotomy or iridectomy. This allows the bulging iris bombe to sink backwards like a punctured ship's sail and is a sure means of preventing further acute attacks. Usually, the fellow eye is at risk of a similar problem and is lasered at the same time. In some patients, the angle of the anterior chamber remains partially occluded by peripheral adhesions from the iris. In these cases, a simple peripheral iridectomy might not be adequate and it might be necessary to carry out a drainage operation, such as a trabeculec-tomy. Most patients with acute narrow-angle glaucoma are cured by surgery, although a small proportion develops cataracts in later years. The prognosis in adequately treated narrow-angle glaucoma is, therefore, good, but in the absence of treatment the result is disastrous.

The treatment of narrow-angle glaucoma has undergone a small revolution over the past few years. This is because a new generation of lasers has appeared, which make it possible to perforate the iris quite simply. The yttrium-aluminum-garnet (YAG) laser has replaced surgical iridectomy in most cases. A special contact lens is used to focus the laser on the peripheral iris, and one or two full-thickness openings in the peripheral iris are created. Following such laser treatment, topical steroids and pupil dilatation are given to minimise the effects of uveitis. Occasionally, trabeculectomy surgery is performed if intraocular pressures remain persistently high despite other treatments.

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