DME: lasers better than steroids

Focal/grid photocoagulation is more effective than intravitreal injections of preservative-free triamcinolone for the treatment of diabetic macular oedema (DME), according to a study published in the July 2008 issue of Ophthalmology. This is the first study to compare long-term laser therapy with corticosteroid treatment for DME.

Neil Bressler, MD, of the Diabetic Retinopathy Clinical Research Network and Johns Hopkins University, Baltimore, US and colleagues conducted a multicentre randomized trial of 693 DME patients (840 eyes) to assess visual acuity, retinal thickness and safety up to two years. Patients were divided into three groups to compare focal/grid photocoagulation (n=330) with 1 mg and 4 mg doses of intravitreal triamcinolone (n=256 and 254, respectively). Patients received re-treatment, if required, at four-month intervals.

In terms of mean visual acuity, 4 mg triamcinolone performed best of the three groups at four months; at one year, there was no statistically significant difference between the three groups; at 16 months and two years, laser therapy performed best, with approximately one-third of eyes in this group demonstrating "substantial improvement" in vision. Optical coherence tomography corroborated these results.

Across both corticosteroid treatment arms, 28% of eyes lost ≥2 lines, compared with 19% of laser-treated eyes. Additionally, intraocular pressure increased ≥10 mmHg from baseline in 33% of the eyes receiving treatment with 4 mg triamcinolone, in 16% of eyes receiving treatment with 1 mg triamcinolone and in 4% of eyes undergoing focal/grid photocoagulation. Cataract surgery was required in 51% of eyes receiving 4 mg triamcinolone, in 23% of eyes receiving 1 mg triamcinolone and in 13% of eyes undergoing laser therapy.

The researchers concluded that not only were the long-term visual acuity outcomes much more favourable following treatment with lasers rather than corticosteroids but also that the incidence of adverse events was lower in the laser treatment arm than in either of the corticosteroid groups.