Correlation between microaneurysm closure rate and reduction in macular thickness following laser photocoagulation of diabetic macular edema.

AIM

To correlate the microaneurysmal closure rate measured on fundus fluorescein angiography (FFA) with reduction in macular thickness observed on optical coherence tomography (OCT) following laser photocoagulation of diabetic macular edema.

MATERIALS AND METHODS

A prospective observational case series. Fifty patients (50 eyes) of type II diabetes mellitus with clinically significant macular oedema (CSME) underwent focal/grid laser photocoagulation. OCT and FFA were performed at baseline and at 2 and 12 weeks following laser photocoagulation to measure the change in macular thickness and the number of leaking microaneurysms respectively. Statistical analysis was performed using paired-ttest and Pearson's correlation test.

RESULTS

A significant reduction in macular thickness was seen at both 2 (P=0.02) and 12 weeks (P<0.0001), most remarkably in the central 1 mm quadrant. However, microaneurysm closure was only 0.67% at 2 weeks, which increased to 89.6% by 12 weeks. The change in retinal thickness correlated significantly with the decrease in the number of leaking microaneurysms at 12 weeks (r=0.597, P<0.0001), but not at 2 weeks (r=-0.228, P=0.112). On OCT, the final reduction in retinal thickness achieved at 12 weeks from baseline correlated significantly with the initial decrease in retinal thickness at 2 weeks (r=0.66, P<0.0001). However, on FFA, the final closure rate of leaking microaneurysms at 12 weeks from baseline did not correlate with the initial closure rate at 2 weeks (r=-0.039, P=0.413).

CONCLUSION

Following laser photocoagulation for CSME, an OCT at 2 weeks is more informative and better correlates with the final outcome than an FFA at 2 weeks.