Abstract:
To investigate the impact of initial foveal thickness on response to subtenon's triamcinolone acetonide (STTA) injection in patients with macular edema.
Retrospective chart review of patients treated with STTA between 1/1/02 and 12/31/03 for CME, CSDME or BRVO was performed. The eyes having 2 or more optical coherence tomography (OCT) measurements, with one on the day of injection and no additional injections between the OCT's, were included. In patients with multiple follow–up OCT's, the smallest foveal thickness value, as determined by OCT software or calipers, was used. Response to injection was calculated as a percent change from initial central foveal thickness.
Patients were stratified into 3 groups based on initial central foveal thickness; Group 1 having a value < 299µm, Group 2 between 300–399µm, and Group 3 being > 400µm. A paired t–test was used to compare the mean pre and post–injection OCT thickness for each group. ANOVA was used to compare the mean percent decrease in OCT thickness between the groups. Significance was assumed to be P<0.05.
For the 31 patients who met the inclusion criteria, 35 eyes were injected 37 times (20 CSDME, 14 CME and 3 BRVO). Mean central foveal thickness decreased from 253.4µm to 214.1µm (15.2%) for Group 1, from 334.7µm to 263.5µm (21.5%) for Group 2, and from 477.5µm to 340µm (26.4%) for Group 3. A paired t–test showed that these decreases were significant for each group. In 6 cases, foveal thickness increased on follow–up:3 in Group 1, 2 in Group 2 and 1 in Group 3. The standard deviation of percent changes were not significantly different between 3 groups (P=0.4661). The best response to STTA was seen between 14.5 weeks (Group 3) to 15.8 weeks (Group 1). ANOVA found no significant difference in the mean percent decrease in OCT thickness for the 3 groups (P=0.5069).
Subtenon's triamcinolone acetonide injection resulted in a significant decrease in central foveal thickness in eyes with macular edema studied. The percent decrease was not significantly impacted by the initial thickness. However, there was a wide variation in the change in foveal thickness after STTA injection between eyes.
Keywords: macula/fovea • drug toxicity/drug effects • injection