Correlation of response to intravitreal bevacizumab treatment between the first and second treated eyes in diabetic macular edema

Purpose: To evaluate whether outcome of bevacizumab treatment in the first treated eye can guide the selection of compound for the second treated eye in patients with bilateral diabetic macular edema. Methods: Demographic, clinical, and optical coherence tomography data were retrospectively collected from consecutive patients who underwent bevacizumab therapy for bilateral diabetic macular edema. Change in central subfield thickness and visual acuity were evaluated and compared between the first treated eye and second treated eye. Results: A total of 66 eyes of 33 patients were included in the study. The mean ± SD follow-up time was 13 ± 5 months. The mean ± SD central subfield thickness at baseline was 464 ± 30 μm in the first treated eye and 461 ± 29 μm in the second treated eye (p = 0.91). Final central subfield thickness was reduced to 392 ± 27 μm in the first treated eye (p = 0.01 compared with baseline) and 416 ± 25 μm in the second treated eye (p = 0.03 compared with baseline). Using ≥5% or ≥10% reduction of central subfield thickness as diagnostic criteria to predict similar magnitude of thickness reduction in the first treated eye yielded a positive and negative predictive value ranging from 46% to 81%, and sensitivity and specificity ranging from 54% to 84%. Regression models did not show correlation between central subfield thickness reduction in first treated eye and the second treated eye at the end of follow-up. Conclusions: Bevacizumab therapy reduced macular thickness in both eyes in bilateral diabetic macular edema. Treatment outcome of the first treated eye could not predict the outcome of the second treated eye. Particularly, failure to reduce central subfield thickness in the first treated eye does not preclude a favorable response to bevacizumab therapy in the second eye.