Letter. Topiramate‐induced acute angle closure glaucoma

Abstract

Sir, I read with interest your ‘Drug notes’ article about topiramate and its use for weight reduction in patients with obesity.1 I note that the other uses of the drug are as an anti-epileptic and for the prevention of migraine. Among the many side effects of the drug, visual disturbances, diplopia and eye pain are frequently mentioned in the literature. I would like to draw the attention of readers to a more serious side effect: acute secondary angle closure glaucoma, which is often bilateral.2, 3 The British National Formulary documents this.4 Many cases have previously been reported by ophthalmologists.2, 3, 5, 6 Now that weight reduction is being considered as an indication1 in addition to the other established uses (epilepsy and migraine), it is possible that the incidence of acute angle closure glaucoma could soon rise. Therefore, primary care practitioners and eye emergency doctors should be alert to the possibility of this occurring, and the presentation and management of these patients. The cases presented seem to be between 30–60 years of age, occur in both sexes, and seem to arise a few weeks after starting topiramate treatment. Patients present with acute onset of myopia with reduction of visual acuity. Acute angle closure glaucoma often occurs bilaterally with very high intra-ocular pressures. Ophthalmologists should be aware that management of these secondary angle closure cases is completely different from the management of the primary acute angle closure glaucomas. Box 1 (above) summarises acute secondary angle closure glaucoma presentation, signs, mechanism of onset, and management. Presentation5-7 • Acute onset of myopia, often bilateral • Reduction in visual acuity • Moderate to severe eye pain, sometimes with halos • History of starting topiramate within a month or so Signs • Possible red eye with corneal oedema • Shallow anterior chambers • Pupils may be fixed or mobile; pressures often high • Lens swollen, anteriorly displaced • B-scan examination showing shallow anterior chamber, angle closure and generalised swelling of ciliary body and choroid Mechanism of onset The onset seems to be due to cilio-choroidal effusion, which tends to push the lens forward due to ciliary and vitreous pressure inducing myopia and angle closure5-7 Management In cases of bilateral angle closures, always ask about topiramate • Stop the medication immediately • Start oral or intravenous carbonic anhydrase inhibitors such as Diamox and topical treatment with brinzolamide or dorzolamide • Do not use pilocarpine; instead use cycloplegia (cyclophentolate) • Some have used laser peripheral iridotomy • Topical steroids to promote decongestion • Iopidine and beta blockers could be useful I hope your readers would appreciate this information. There are no conflicts of interests declared.