The fellow eye effect of unilateral intravitreal conbercept injections in eyes with diabetic macular edema

Aims To investigate whether intravitreal conbercept injection affects contralateral untreated eyes in bilateral diabetic macular edema (DME) patients. Methods In this retrospective study, 15 patients (30 eyes) with type 2 diabetes were followed after bilateral DME diagnosis in the Department of Ophthalmology, Peking Union Medical College Hospital from 2015 to 2018. Patients underwent examinations including best corrected visual acuity (BCVA), slit-lamp microscopy, indirect ophthalmoscope, color fundus photography, fundus fluorescein angiography, optical coherence tomography, and glycated hemoglobin (HbA1c). Each patient received conbercept (0.5 mg) intravitreally in the severe eye. Nonparametric Wilcoxon signed-rank tests and Pearson's correlation coefficient were used to assess changes in BCVA and central retinal thickness (CRT) and relations between BCVA changes in treated and untreated eyes, respectively. Results The mean follow-up time was 10.60 +/- 2.29 months, and the mean injection number of 15 treated eyes was 9.13 +/- 0.68. HbA1c remained below 10% during treatment with no significant changes between the initial and final visits (7.81 +/- 1.17 vs 7.62 +/- 1.19%) (P = 0.576). In untreated eyes, CRT significantly decreased from the initial to final visits (368.93 +/- 125.45 vs 306.27 +/- 89.70 mu m) (P = 0.028). In untreated eyes, BCVA showed no significant difference between the initial and final visits (0.38 +/- 0.30 vs 0.40 +/- 0.30 logMAR) (P = 0.937), but BCVA changes in treated and untreated eyes were positively correlated (r = 0.527, P = 0.044). Conclusions Intravitreal conbercept injection results in decreased CRT and increased BCVA in untreated eyes, which is consistent with the changes in treated eyes for patients with bilateral DME.