Treat-and-extend regimens of anti-vascular endothelial growth factor therapy for retinal vein occlusions: a systematic review and meta-analysis

Objective: To investigate treat-and-extend (T&E) regimens of anti-vascular endothelial growth factor (anti-VEGF) therapy for the treatment of macular oedema secondary to retinal vein occlusions (RVOs). Methods: Ovid MEDLINE, Ovid EMBASE and CENTRAL were searched on 25 February 2021. Randomized controlled trials, cohort studies, case–control studies and case series were included. The primary outcome was the change in Early Treatment Diabetic Retinopathy Score (ETDRS) letters from baseline. Conversions from Snellen to ETDRS letters were performed utilizing a published protocol. Secondary outcomes included improvement in retinal thickness from baseline, number of anti-VEGF injections and frequency of adverse events. Outcomes were examined at 12 and 24 months. Certainty of evidence was assessed utilizing GRADE (Grading of Recommendations Assessments, Development and Evaluations) guidelines. Results: Seven hundred eighty-six eyes from 16 studies were included. Meta-analysis demonstrated a mean improvement of 15.7 (95% CI: 13.3–18.0) ETDRS letters at 12 months. Central retinal thickness improved 269.7 μm (95% CI: 233.64–305.90) at 12 months. Injections were performed 8.1 (95% CI: 7.4–8.7) and 13.1 (95% CI: 9.4–16.8) times at 12 and 24 months respectively. Adverse events were infrequent across all studies. Grading of Recommendations Assessments, Development and Evaluations (GRADE) certainty of evidence was very low across all outcomes. Conclusions: The results support the viability of T&E regimens for the treatment of macular oedema secondary to RVOs.