To evaluate the effects of a single intravitreal bevacizumab injection on retinal vessel diameter, intraocular pressure (IOP), retinal nerve fiber layer (RNFL) thickness and the optic disc in patients with diabetic macular edema (DME).

In this retrospective study, 63 eyes with DME were included. All patients received an intravitreal injection of 1.25 mg bevacizumab. We reviewed retinal vessel diameter, IOP RNFL thickness and vertical cup-to-disc (C/D) ratios at the baseline and 7 days, 1 month, 3 months and 6 months after injection. The diameter of the central retinal arteries and veins were measured using retinal photographs. The central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE) were calculated using the revised Parr-Hubbard formula. RNFL thickness was obtained using optical coherence tomography. The vertical C/D ratio of the optic disc was evaluated using stereoscopic optic disc photography.

After bevacizumab injection, the CRAE significantly decreased at 7 days and 1 month postoperatively compared to baseline ( p < 0.001 and p = 0.036, respectively). However, the changes in the CRAE at 3 months and 6 months were not statistically significant ( p = 0.992 and p = 0.342, respectively). There were no statistically significant changes in the CRVE, mean IOP, RNFL thickness and vertical C/D ratios of the optic disc.

A single intravitreal bevacizumab injection transiently decreased the diameters of central retinal arterioles, but induced no significant changes in central venular diameter, mean IOP, RNFL thickness or vertical C/D ratios of the optic disc.