Correlation of visual acuity and macular thickness measured by optical coherence tomography in patients with persistent macular edema.

Purpose: The purpose of this study was to evaluate the correlation between best-corrected visual acuity (BCVA) and macular thickness in patients with persistent macular edema treated with a dexamethasone intravitreal drug delivery system (dexamethasone DDS).
Methods: In a randomized, multicenter, controlled, parallel-group, dose-ranging study, patients with macular edema lasting at least 90 days despite treatment were randomized to observation or treatment with 350- or 700-microg dexamethasone DDS. Macular thickness was assessed in 80 patients using optical coherence tomography. Best-corrected visual acuity was measured using Early Treatment Diabetic Retinopathy Study methodology.
Results: At baseline, macular thickness was significantly inversely correlated with BCVA (r = -0.406, P < 0.001). Patients treated with 350- or 700-microg dexamethasone DDS showed a significant decrease in macular thickness from baseline to Day 90 (P = 0.002). In the 700-microg dexamethasone DDS treatment group, there was a modest inverse correlation between changes in macular thickness from baseline to Day 90 and improvement in BCVA (r = -0.530, P = 0.009). In the 350-microg dexamethasone DDS treatment group, the correlation was weaker and not statistically significant (r = -0.206, P = 0.304).
Conclusion: The correlation between baseline BCVA and macular thickness in patients with persistent macular edema was modest. Improvement in BCVA after treatment with 700-microg dexamethasone DDS was consistent with changes in macular thickness measured using optical coherence tomography.