The detrimental effects of delayed intravitreal anti-VEGF therapy for treating retinal pathology: lessons from a forced test-case

Purpose: Determine the anatomical consequences of delaying intravitreal injection (IVI) therapy with anti-vascular endothelial growth factor (anti-VEGF) in patients using treat-and-extend (T&E) protocol. Methods: Retrospective medical record review of consecutive patients receiving intravitreal anti-VEGF therapy using T&E protocol prior to and during the COVID-19 pandemic. Results: The study included 923 eyes of 691patients; 58.8% (543 eyes), 25% (231 eyes), and 16.2% (149 eyes) had nvAMD, DME, and RVO, respectively. Mean (± SD) patient age was 74.5 ± 11.7 years. Overall, 56.3% of cases had a delay in therapy of ≥ 7 days; specifically, 56.2%, 61.5%, and 49.0% of nvAMD, DME, and RVO cases, respectively, had a delay. The median delay in days, among cases ≥ 7 days late was 21 (IQR 7 to 42) days, with 21(IQR 7 to 45), 22.5(IQR 8 to 42), and 14(IQR 7 to 33.5) days of delay among patients with nvAMD, DME, and RVO, respectively. Delaying therapy by ≥ 7 days resulted in increased CST in 47.5%, 58.5%, and 58.9% of nvAMD, DME, and RVO cases, respectively, with a significant correlation between the length of treatment delay and the increase in CST (Spearman’s rho: 0.196; p < 0.001). Conclusions: Delayed IVI treatment in eyes treated with T&E protocol was associated with increased macular thickness with potential consequences with respect to visual outcome.