A 10-Year Summary of the Safety and Economy of a New Method for Dispensing Ranibizumab/Conbercept in Same-day Bilateral Intravitreal Injection Using a Single Vial Running title: Bilateral Anti-VEGF Injection Using a Single Vial

Abstract Purpose Analyze the safety and economy of a new method for dispensing ranibizumab/conbercept in same-day bilateral intravitreal injection using a single vial. Methods This is a retrospective study involving a total of 2775 patients 7646 injections during 2012 to 2021. 541 patients receiving same-day bilateral intravitreal injection using a single vial were defined as bilateral injection group and 2234 patients receiving unilateral injection were defined as unilateral injection group. The dispensing method was drawing all ranibizumab/conbercept drugs by the prepackaged syringe, dividing drugs by a disposable aseptic insulin syringe drawing from the prepackaged syringe. The equipment used in bilateral injection was new for each eye. Data of gender, age, diagnosis, the kind of anti-VEGF drugs and the occurrence of infectious endophthalmitis were recorded. The cost of bilateral injection and unilateral injection for the patients requiring bilateral treatment were compared. Results The mean age of bilateral injection group and unilateral injection group was 61.73 ± 13.41 and 62.23 ± 15.48 years old respectively (t = 0.67, P > 0.05). The incidence of infectious endophthalmitis was 0.026% (2/7646) totally. The incidence of infectious endophthalmitis in bilateral injection group was (1/2464, 0.041%) and in unilateral injection group was (1/5182, 0.020%). There was no significant difference between two groups (χ2 = 0.29, P > 0.05). No bilateral infectious endophthalmitis occurred. Bilateral injection using a single vial saved about 46.5% cost when comparing with unilateral injection. Conclusions The same-day bilateral intravitreal anti-VEGF therapy using a single vial didn’t increase the incidence of infectious endophthalmitis when comparing with unilateral injection and reduced nearly a half treatment cost.