Macular Thickness Fluctuation as a Biomarker: Impact on Visual Acuity Following Antivascular Endothelial Growth Factor Therapy for Diabetic Macular Edema

<b>Purpose:</b> To evaluate the association between central subfield thickness (CST) fluctuations and visual acuity (VA) outcomes in eyes with diabetic macular edema (DME) undergoing antivascular endothelial growth factor (anti-VEGF) therapy. <b>Methods:</b> We conducted a retrospective review of patients with DME who initiated treatment between 2016 and 2017 at a multicenter retina practice. Eligible eyes had a follow-up period of 40 weeks or longer and received 3 or more anti-VEGF injections. CST fluctuations were determined using the SD of CST measurements across visits and stratified into quartiles. Stepwise linear regression analysis determined the impact of factors on best-corrected VA (BCVA). <b>Results:</b> A total of 499 eyes from 333 subjects were included. Eyes received a mean of 15.7 anti-VEGF injections (range, 3-50) over 18.8 visits (range, 3-67) across a mean of 121.3 weeks (range, 40.6-230.3). Mean (± SD) CST at DME diagnosis and at the final visit was 353.7 ± 134.8 µm and 287.2 ± 78.9 µm, respectively; mean change was 42.4 ± 47.3 µm. Eyes with the greatest CST fluctuations had worse baseline and final VA, as well as baseline and final CST (<i>P</i> < .0001). Each 100 μm increase in CST SD was independently associated with 12.9 fewer letters read at 121.3 weeks. Factors independently associated with better final VA were smaller CST SD, smaller final CST, a greater number of anti-VEGF injections, and younger age. <b>Conclusions:</b> Consistent with previous analyses, increased CST fluctuation was independently associated with worse final BCVA. Large CST fluctuations may serve as a poor prognosticator for visual outcomes among patients with DME.