Purpose Antivascular endothelial growth factor (anti-VEGFs)—bevacizumab is routinely utilised for the treatment of diabetic macular oedema (DME). We plan to evaluate the impact of bevacizumab on the central subfield macular thickness (CSMT) of the treated and untreated eye.

Methods A sequential group of patients with bilateral DME who were treated with unilateral bevacizumab injection were assessed preinjection and postinjection by Spectral Domain-Optical Coherence Tomography (SD-OCT) by CSMT.

Results Thirty-one patients, 20 male and 11 female, were evaluated. Seven patients had type 1 diabetes mellitus and 24 had type 2 diabetes mellitus. In regard to the duration of disease, 23 patients had diabetes for more than 10 years, seven patients had the condition for 5–10 years and one patient for more than 5 years. Mean age of the patients was 60.48 years (SD±7.13) with the range of 46–72 years. Mean follow-up was 28 days (range 26–35 days). The eyes which received intravitreal injection had median CSMT of 473.2 µm(range 321–566 µm). The CSMT of the contralateral eye had median of 347.6 µm (range 357–437 µm). A median reduction of −132 µm (range 93–156 µm) could be observed in the treated eye and −18 µm (range 15–22) in the untreated eye after treatment. Our study also found that eyes with greater CSMT, when injected with bevacizumab, produced higher responses in the contralateral eye (R² 0.538, P<0.05).

Conclusions Patients with bilateral DME treated with bevacizumab in one eye produced a bilateral response. Eyes with greater CSMT due to DME elicited higher levels of response in the untreated eye.