OCT Biomarkers as Functional Outcome Predictors in Diabetic Macular Edema Treated with Dexamethasone Implant

PURPOSE: Identification and characterization of patients with diabetic macular edema (DME) are important for individualizing treatment and optimizing outcome. We investigated OCT biomarkers for DME treated by intravitreal dexamethasone (DEX) implant. DESIGN: Multicenter, retrospective, observational cohort study. PARTICIPANTS: A total of 299 eyes from 284 patients treated with DEX implant for DME (naïve, n = 209; refractory, n = 90). Baseline best-corrected visual acuity (BCVA) was between 0.3 and 1.0 on a logarithm of minimum angle of resolution visual chart. METHODS: The OCT scans previous to DEX implants were evaluated for submacular fluid, size and location of cystoid changes, inner segment-outer segment (IS-OS) continuity, quantity and location of hyperreflective foci (HRF), vitreomacular interface abnormalities, and epiretinal membrane. The BCVA and central macular thickness were recorded at baseline and at 1, 2, and 4 months after treatment with DEX implants. Correlations between OCT measures and visual outcome were analyzed using the generalized estimating equations procedure. MAIN OUTCOME MEASURES: The correlation between spectral-domain (SD) OCT measures at baseline and BCVA response (mean change from baseline; categorized improvement [<5, 5-9, or ≥10; Early Treatment Diabetic Retinopathy Study letters] in BCVA) after treatment with a DEX implant. RESULTS: The presence of subretinal fluid (odds ratio [OR], 1.98; 95% confidence interval [CI], 1.23-3.20; P = 0.01), absence of HRF (OR, 3.66; 95% CI, 1.40-9.62; P = 0.01), and integrity of the IS-OS layer (OR, 2.09; 95% CI, 1.30-3.37; P = 0.003) were all predictive of better visual outcome after treatment with DEX implants. Although eyes with naïve DME gained more vision than refractory eyes (P < 0.001), the predictive value of OCT findings did not differ according to this classification. CONCLUSIONS: Spectral-domain OCT is useful in identifying various imaging findings in DME. Among eyes with DME, those with submacular fluid, no HRF, and a continuous IS-OS layer responded better to DEX implants than those without these features. These findings call for further study of combinations of OCT and metabolic biomarkers.