To evaluate the effect of diabetic retinopathy on choroidal thickness and the changes of choroidal thickness after intravitreal bevacizumab injection (IVB) in diabetic patients.

The present study included 105 patients (105 eyes). Patients were classified into 6 groups: control group (A); no change (B), mild (C), moderate (D), and severe (E) non proliferative diabetic retinopathy (NPDR); and proliferative diabetic retinopathy (PDR) (F), with 15 diabetic patients in each group. All patients underwent enhanced depth imaging spectraldomain optical coherence tomography (EDI OCT) to evaluate choroidal thickness. An additional 15 patients (15 eyes) with diabetic retinopathy treated with IVB were also included. These patients underwent EDI OCT before and 1 month after IVB.

Mean choroidal thickness was significantly thinner in the moderate and severe NPDR, and PDR groups compared with the control group. Moreover, when comparing sequential stages of diabetic retinopathy progression, the choroidal thickness in the moderate NPDR stage and PDR stage was found to be significantly thinner than in the mild and severe NPDR, respectively. Additionally, choroidal thickness was 187.3 µm before IVB and significantly decreased to 168.9 µm 1 month after IVB ( p < 0.05).

Choroidal thickness is related to the severity of diabetic retinopathy and is significantly decreased after IVB.