BCVA as an Early Indicator in Treat-and-Extend Management of DME: READ-3 Post-hoc Analysis

Purpose To determine whether clinically meaningful changes in best-corrected visual acuity (BCVA) can precede or coincide with changes in central retinal thickness (CRT) in diabetic macular edema (DME) under a treat–and–extend regimen, even after complete resolution of macular edema. Design Post–hoc analysis of the READ–3 clinical trial. Participants 21 eyes from 21 READ–3 participants who achieved CRT <250 µm (no OCT–detectable edema) at 6 months. Methods Patients received 5 monthly ranibizumab injections (loading phase), then were monitored monthly through 24 months with as–needed retreatment if OCT showed recurrent edema (treat–and–extend phase). We defined a significant BCVA change as ≥4 ETDRS letters and a significant CRT change as ≥30 μm on OCT, and we analyzed the temporal B–C lag between functional (BCVA) and anatomical (CRT) changes. Main Outcome Measures Timing and sequence of BCVA vs. CRT changes per patient, and injection–free interval durations. Results Mean age was 65.6 ± 10.7 years. By month 6 (post-loading), all 21 eyes had resolved edema (CRT <250 μm). In this initial treatment phase, 9 eyes (42.9%) showed BCVA improvement (≥4 letters) concurrently with CRT reduction (≥30 microns); 8 eyes (38.1%) showed BCVA improvement one month after CRT improvement; and 4 eyes (19.0%) exhibited a longer BCVA lag of 2–5 months. During the 6–24–month treat–and–extend phase, BCVA and CRT changes coincided in 5 eyes (23.8%). In another 5 eyes (23.8%), a BCVA decline preceded any CRT increase by a median of 3 months (range 1–12), serving as an early warning of relapse. Four eyes (19.0%) showed CRT thickening prior to BCVA loss. The remaining 7 eyes (33.3%) had no observed recurrent edema or vision loss during follow-up, owing to proactive retreatment before changes manifested. Conclusions BCVA fluctuations often mirrored CRT changes and, in some cases, preceded structural relapse. These findings suggest BCVA monitoring could serve as an independent indicator of DME activity, potentially enabling earlier intervention in a treat–and–extend paradigm even after the macula is initially dried. A home BCVA monitoring strategy, if validated, might reduce reliance on OCT for routine surveillance and improve patient outcomes where access to OCT is limited.