To evaluate microaneurysm (MA) turnover and changes in central retinal thickness after intravitreal dexamethasone implantation or intravitreal bevacizumab injection to treat diabetic macular edema.

Sixty eyes with diabetic macular edema were evaluated. In all, 30 eyes received intravitreal dexamethasone implants (group A) and 30 received bevacizumab injections (group B). All patients were followed-up at 3 and 6 months. MA formation, disappearance, and turnover (MA formation rate minus disappearance rate) were evaluated. When the disappearance rate was greater than the formation rate (so the turnover was ≤0), the microaneurysms were considered to have resolved. Central retinal thickness (CRT) was measured using optical coherence tomography at all visits.

In group A, MA turnover was 86.6% at 3 months and 53.3% at 6 months, and thus decreased slightly over time, but was not eliminated. In group B, MA turnover was 56.6% at 3 months and 13.3% at 6 months; the between-group difference was statistically significant ( p = 0.014). CRT decreased in both groups, but significantly less so in group B 3 months after injection. However, no significant between-group difference was apparent 6 months after injection.

There were no significant between-group differences in either CRT or MA turnover 3 months after injection. However, at 6 months, dexamethasone implantation showed slightly better results than intravitreal bevacizumab injection. However, further research on long-term MA turnover is required.