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It is a form of secondary angle closure glaucoma following intraocular surgery to the anterior segment of the eye. Such procedures include filtering surgery for glaucoma, cataract extraction and iridectomy, although it typically follows surgery for angle closure glaucoma.
Both the central and peripheral anterior chamber is shallow and intraocular pressure (IOP) is elevated. This may occur fairly quickly following surgery or there may be a considerable latent period, perhaps several years. It is thought that the usual anterior flow of aqueous is disrupted with the anterior hyaloid face of the vitreous becoming increasingly permeable allowing aqueous to pool in the vitreous chamber.
Ultrasound biomicroscopy has indicated that this increase in volume of the vitreous causes the ciliary body, lens and iris to move forward, thus shallowing the anterior chamber and compromising aqueous outflow.
In the early stages of this process, symptoms may be minimal. Alternatively, the patient may present with a red, photophobic and painful eye.
IOP is elevated, potentially to very high levels. The anterior chamber is shallow both centrally and peripherally. A peripheral iridotomy, if present, is patent. There is an absence of pupillary block.
This is a rare complication following intraocular surgery. Up to 4 per cent of patients undergoing surgery for closed angle glaucoma may manifest this condition.
Differential diagnosis
Other conditions where the patient may present with a shallow anterior chamber and raised IOP, such as pupillary block and closed angle glaucoma, plateau iris, choroidal detachment and suprachoroidal haemorrhage.
Management
The objective of treatment is to break the attack by reforming the anterior chamber and reducing IOP.
Topical medication
Malignant glaucoma typically responds poorly to medical therapy. However, initially, medical management is usually attempted. Cycloplegic and mydriatic agents such as atropine and phenylephrine are prescribed. Cycloplegics relax the ciliary muscle and create more taut lenticular zonules which may cause a posterior displacement of the iris and lens.
Aqueous suppressants and hyperosmotic agents promote vitreal dehydration thereby reducing its volume. The use of miotics is contraindicated.
Laser and incisional surgery
If medical therapy proves fruitless, surgery must be considered. An attempt should be made to disrupt the posterior capsule and the anterior hyaloid face of the vitreous if the patient is aphakic or pseudophakic with the YAG laser.
In the phakic patient, a lensectomy and vitrectomy may be appropriate. Filtration surgery is unlikely to be effective.