For Bilateral Uveitic Glaucoma, It May be Best to Operate on Second Eye Sooner than Later

In approximately three-quarters of patients, uveitis is bilateral. Of these, approximately 40% experience elevated intraocular pressure sometime during the course of the disease. And if these patients go untreated, the result is often chronic uveitis and poor vision.

Topical hypotensive agents can control intraocular pressure (IOP) in about one-quarter of patients, and oral carbonic anhydrase inhibitors (CAI) like acetazolamide (Diamox/Teva) can control it in another 62%. Yet 35% of adults and 60% of children with uveitic glaucoma eventually need filtration surgery for glaucoma either because they become dependent on an oral CAI or because maximal tolerated medical therapy cannot control IOP.

Most ophthalmologists end oral CAI therapy soon after filtration surgery to prevent hypotony and ensure maintenance of aqueous flow. However, the eye that does not receive surgery may also depend on an oral CAI for IOP control. If so, IOP could become markedly elevated in the second eye when this therapy is ended.

As a result, depending on the severity of the IOP elevation and the time between filtration surgeries, glaucoma may progress even more in the second eye than in the first. And if this is so, earlier glaucoma surgery in the second eye could improve its prognosis.

To determine whether greater glaucoma progression occurred in the second eye of bilateral uveitic glaucoma patients after their first eye received filtration surgery, a British-Malaysian team pursued a retrospective study of 60 eyes from 30 such patients who had glaucoma surgery in both eyes at separate times. To do so, the team reviewed charts of patients seen at the uveitis clinic of Moorfields Eye Hospital in London, UK, from May, 2010, to November, 2012.

Before surgery, the difference in IOP between the first and the second eye was not statistically significant (P = 0.15). After surgery, reduction in IOP was approximately 4 percentage points greater in the first eye than in the second one. However, at the final visit, the mean IOPs of the first and the second eyes did not differ (P = 0.2). Moreover, logMAR readings did not change significantly before vs. after surgery or between the first and second eye surgeries. However, the number of second eyes with a cup-to-disc ratio of >0.7 increased by 23% compared with the number of first eyes with such a ratio.

The team also used Progressor software to measure progression by visual field (VF). They found that, in 5 second eyes, progression occurred at a median of 5 (range 1—11) locations in 23 available VFs, or 22%. In contrast, progression occurred in only one first eye. Nevertheless, they found no significant difference in the mean global rate of progression of the second eye (−0.76 ± 2.1 dB/yr) compared with that of the first (−0.9 ± 1.6 dB/yr; P = 0.17).

These findings led the team to conclude that, in patients with bilateral uveitic glaucoma who needed filtration surgery, the second eye that received surgery had more progressed points on the visual field and greater glaucomatous disc progression than the first eye. These findings suggest that, at least in some eyes, earlier surgical treatment of the second eye could improve its prognosis.

The study, “Difference in glaucoma progression between the first and second eye after consecutive bilateral glaucoma surgery in patients with bilateral uveitic glaucoma,” was published in the December, 2016, issue of Graefe's Archive for Clinical and Experimental Ophthalmology.

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