A randomized trial comparing intravitreal triamcinolone acetonide and focal/grid photocoagulation for diabetic macular edema

Abstract

Objective: To evaluate the efficacy and safety of 1-mg and 4-mg doses of preservative-free intravitreal triamcinolone in comparison with focal/grid photocoagulation for the treatment of diabetic macular edema (DME).

Design: Multicenter, randomized clinical trial.

Participants: Eight hundred forty study eyes of 693 subjects with DME involving the fovea and with visual acuity of 20/40 to 20/320.

Methods: Eyes were randomized to focal/grid photocoagulation (n = 330), 1 mg intravitreal triamcinolone (n = 256), or 4 mg intravitreal triamcinolone (n = 254). Retreatment was given for persistent or new edema at 4-month intervals. The primary outcome was evaluated at 2 years.

Main outcome measures: Visual acuity measured with the electronic Early Treatment Diabetic Retinopathy Study method (primary), optical coherence tomography-measured retinal thickness (secondary), and safety.

Results: At 4 months, mean visual acuity was better in the 4-mg triamcinolone group than in either the laser group (P<0.001) or the 1-mg triamcinolone group (P = 0.001). By 1 year, there were no significant differences among groups in mean visual acuity. At the 16-month visit and extending through the primary outcome visit at 2 years, mean visual acuity was better in the laser group than in the other 2 groups (at 2 years, P = 0.02 comparing the laser and 1-mg groups, P = 0.002 comparing the laser and 4-mg groups, and P = 0.49 comparing the 1-mg and 4-mg groups). Treatment group differences in the visual acuity outcome could not be attributed solely to cataract formation. Optical coherence tomography results generally paralleled the visual acuity results. Intraocular pressure increased from baseline by 10 mmHg or more at any visit in 4%, 16%, and 33% of eyes in the 3 treatment groups, respectively, and cataract surgery was performed in 13%, 23%, and 51% of eyes in the 3 treatment groups, respectively.

Conclusions: Over a 2-year period, focal/grid photocoagulation is more effective and has fewer side effects than 1-mg or 4-mg doses of preservative-free intravitreal triamcinolone for most patients with DME who have characteristics similar to the cohort in this clinical trial. The results of this study also support that focal/grid photocoagulation currently should be the benchmark against which other treatments are compared in clinical trials of DME.

Figure 1

Flow chart showing visit completion rate according to treatment group over the two years of follow up.

Figure 2

Change in visual acuity from baseline to each visit through 2 years according to treatment group. The top portion of the figure displays the median visual acuity in each treatment group. In the bottom portion, the top bars represent the percentage of eyes in each treatment group (solid is laser group [L], striped is 1 mg triamcinolone group [1], dotted is 4 mg triamcinolone group [4]) with an improvement in the visual acuity letter score of 5 to 9 (black segments), 10 to 14 (dark gray segments), and 15 or more (light gray segments); the bottom bars represent the proportion of eyes in each treatment group (solid is laser group [L], striped is 1 mg triamcinolone group [1], dotted is 4 mg triamcinolone group [4]) with a worsening in the visual acuity letter score of 5 to 9 (black segments), 10 to 14 (dark gray segments), and 15 or more (light gray segments).

Figure 3

Effect of treatment on the central subfield thickness, measured with optical coherence tomography (OCT), at each visit according to treatment group. The top portion of the figure displays the median thickness in each treatment group. The bars in the bottom portion represent the proportion of eyes in each treatment group with thickness <250 microns.