To investigate retinal vascular caliber changes with Spectral Domain OCT after intravitreal bevacizumab injection in diabetic macular edema patients.

Thirty-four eyes of 29 diabetic macular edema patients who were intravitreously injected with bevacizumab (1.25 g/0.05 ml) were studied. Twenty-four fellow eyes of 24 patients with bevacizumab injection were also recruited as a control group. We measured retinal vascular caliber a distance of 0.5-1 disc sizes from the disc margin with Spectral Domain OCT at baseline and 1-month and 3-month follow-up visits. Central macular thicknesses were also measured.

Over the 3 months of study, there was a significant reduction of arteriolar caliber compared to baseline ( p = 0.024), There was significant reduction of venular caliber at 1 month ( p = 0.001) and 3 months ( p = 0.000) compared to baseline. Venular caliber reduction at the 3-month follow-up was significantly correlated with central macular thickness (R = 0.487, p = 0.003).

Retinal venular caliber reduction was significant at 1- and 3-month follow-up, and arteriolar caliber reduction was significant at 3-month follow-up compared to baseline. After 3 months of treatment, venular caliber reduction was correlated with reduction of central macular thickness.