Abstract:
To determine the effect of subtenon's injections of triamcinolone acetonide (STTA) on central foveal thickness as measured by OCT in eyes with clinically significant diabetic macular edema (CSDME) or cystoid macular edema (CME).
Retrospective chart review of patients treated with STTA for CSDME or CME between 01/01/02 and 12/31/03 was performed. Only the eyes that had two or more OCT measurements of the foveal central thickness, one taken on the day of the injection and the other at follow–up, were included. The response to injection was calculated as percentage decrease in the central foveal thickness with thickness at the time of injection as the denominator. For the patients who had an increase in thickness, the percentage was entered as a negative percentage. Response to STTA for CSDME and CME were analyzed statistically using a 2 sample t–test.
Of the 35 eyes of 31 patients who met the inclusion criteria, 37 total injections were performed. For these 37 injections, the mean decrease in central foveal thickness was 20.8% (SD + 24.7%). The follow–up period varied from patient to patient. 20/37 injections were preformed for CSDME. The mean response for CSDME group was 9.6% decrease (range: –32% to 38%). 17/37 injections were performed for CME. The mean response for CME group was 33% decrease (range: 5% to 77% ). Statistical analysis revealed equivalent variances by F test but a statistically significant difference in mean decrease in thickness between the two groups( P= 0.0011) using a 2 sample t– test. A similar analysis of duration of time between the two OCT measurements revealed equivalent variances for the CME (s.d. 10.2) and CSDME (11.1) groups by F–test. The means for the CME (15.0 weeks) and CSDME (15.65) groups were not statistically significant by 2 sample t–test (P= 0.5).
These results indicate that CME patients are more responsive to STTA than CSDME patients. Wide ranging differences in the time interval between the two OCT measurment were not statistically different between the two groups. Thus, one group's response was not due to having follow–up measurements performed sooner or later after the injection.
Keywords: macula/fovea • drug toxicity/drug effects • injection