Anti-VEGF Dosing Intervals for Diabetic Macular Edema: Treat-and-Extend Versus Fixed Regimens

Abstract

Introduction: Diabetic macular edema (DME) requires repeated anti-VEGF injections. Treat-and-extend (T&E) protocols may reduce visit burden compared to fixed monthly or bimonthly regimens. Methods: Systematic review of 9 RCTs (n=2,847) comparing T&E (starting monthly, extending by 2 weeks if stable) versus fixed dosing (e.g., ranibizumab 0.3 mg monthly or aflibercept 2 mg every 8 weeks after loading). Primary outcome: change in best-corrected visual acuity (BCVA) at 12 and 24 months. Secondary: injection frequency, central subfield thickness (CST). Results: Mean BCVA gain was similar at 12 months (T&E +9.8 letters, fixed +10.2 letters, p=0.48) and 24 months (T&E +10.1, fixed +10.3). CST reduction also similar. T&E required 25% fewer injections over 2 years (14.2 vs 18.9, p<0.001). No difference in endophthalmitis or intraocular inflammation. Discussion: T&E achieves equivalent visual outcomes with fewer office visits, improving adherence and reducing healthcare costs. Conclusion: Treat-and-extend anti-VEGF protocol is non-inferior to fixed dosing for DME and should be standard practice for compliant patients.