Tip of the Month
Publishing date: March 2013
The Science behind the Tip
Malignant glaucoma or aqueous misdirection is a rare but feared complication of anterior segment surgery. It occurs in eyes with a shallow anterior chamber despite a patent iridotomy. Through a yet poorly understood mechanism, diversion of aqueous flow into the posterior segment causes a persistent, though not always pronounced intraocular pressure rise. A myopic shift in refraction as the lens is pushed forward is a warning sign. Imaging techniques can demonstrate a ciliary body compressed against the iris as a pathognomonic sign.
Cycloplegics-mydriatics (atropine and phenylephrine), tightening the lens zonules and pulling the lens backwards, together with aqueous suppressants (carbonic anhydrase inhibitors, ß-blockers and brimonidine) and osmotic agents (mannitol) are used to control the immediate situation (1). Although this may be curative, often subsequent Yag-laser capsulotomy and hyaloidotomy is needed (1). Eventually surgery involving vitrectomy and in phakic patients phacoemulsification may be performed (1-3).
Sometimes however, an alternative therapy to surgery may be needed. Some patients, particularly those with only one functional eye, may refuse surgery. Further, surgeries can fail (1-3). In these cases, a minimal therapy with cycloplegics can be continued (3). There is no loss of their intraocular pressure-lowering efficacy over time. This therapy is indefinite, as there is a high chance of relapse if it is discontinued (2,3). Should an allergic reaction to atropine occur, then it can be substituted by topical hyoscine (3).
Contributor: Ann Hoste, Antwerp
1. Shahid H and Salmon JF. Malignant Glaucoma: A Review of the Modern Literature. J Ophthalmol. 2012; 852659. Published online doi: 10.1155/2012/852659PMCID: PMC3321564.
2. Debrouwere V, Stalmans P, Van Calster J, et al. Outcomes of different management options for malignant glaucoma: a retrospective study. Graefes Arch Clin Exp Ophthalmol. 2012;250:131-41.
3. Ruben S, Tsai J, Hitchings R. Malignant glaucoma and its management. Br J Ophthalmol. 1997:81:163-67.
Tip Reviewer: Roger Hitchings
Tip Editors: Ann Hoste, John Salmon and John Thygesen