Selective laser trabeculectomy may prevent IOP elevation after steroid injection for diabetic macular edema

This prospective case series published in the December 2011 issue of the American Journal of Ophthalmology examined the efficacy of selective laser trabeculoplasty (SLT) for preventing an increase in IOP after intravitreal triamcinolone acetonide injection for diabetic macular edema. The authors randomized 31 diabetic macular edema patients with baseline IOP of 21 mmHg or higher to SLT before triamcinolone acetonide injection or to injection treatment only (controls). Their results suggest that in this population, prophylactic SLT may prevent the IOP elevation that can follow intravitreal triamcinolone acetonide injection.

Subjects underwent SLT a mean of 8.3 days before injection. Mean baseline IOP was similar between the study and control groups (21.6 mmHg versus 21.5 mmHg; P = 0.98).

Mean IOP after injection was also similar between the groups at one day (17.0 mmHg in the study group and 19.5 mmHg in the control group; P = 0.23) and one week (16.9 mmHg and 18.4 mmHg, respectively; P = 0.49) after injection. However, at between one and six months’ follow-up, IOP was significantly lower in the prophylactically-treated group (16.4 mmHg versus 20.8 mmHg at one month, P = 0.003; 15.8 mmHg versus 18.3 mmHg at three months, P = 0.01; and 15.7 mmHg versus 17.1 mmHg at six months, P = 0.03).

Half of the control group had an IOP of 21 mmHg or greater after treatment and required antiglaucoma eye drops, compared to none of the patients in the SLT group. Among patients treated with SLT, two experienced a mild transient anterior chamber reaction and three reported ocular discomfort.

The authors note that IOP elevation is a common side effect of intravitreal triamcinolone injection, and its rate increases in patients with higher baseline IOP. Although topical medication usually helps, surgical intervention is sometimes required. Therefore, they conclude that there may be advantages to injecting intravitreal triamcinolone before SLT in patients with a baseline IOP of at least 21 mmHg and planned treatment with a 4-mg intravitreal triamcinolone injection for diabetic macular edema.