Prevalence and Optical Coherence Tomography Biomarker Profile in Diabetic Macular Edema Among Occidental Mexican Patients

Background and Objectives: Diabetic macular edema (DME) is a heterogeneous complication of diabetic retinopathy, and optical coherence tomography (OCT) biomarkers may provide information beyond central retinal thickness. Evidence on the OCT biomarker profile of Mexican patients with DME remains limited. This study aimed to characterize OCT biomarkers in patients with DME from a tertiary referral center in western Mexico and evaluate their associations with clinical characteristics and best-corrected visual acuity (BCVA). Materials and Methods: We conducted a retrospective cross-sectional study of adults with diabetic retinopathy and DME. Clinical records and OCT scans were reviewed. Biomarkers included central macular thickness, intraretinal cysts, subretinal fluid, hyperreflective foci, ellipsoid zone disruption, external limiting membrane disruption, and disorganization of the retinal inner layers (DRIL). Associations with glycated hemoglobin, retinopathy severity, diabetes treatment, and BCVA were analyzed. Results: Fifty-seven patients and 88 eyes were included. The mean age was 59.6 ± 10.3 years, the mean diabetes duration was 15.9 ± 7.1 years, and the mean HbA1c was 8.5 ± 0.9%. The mean BCVA was 1.24 ± 0.59 logMAR, and the mean central macular thickness was 427.6 ± 190.8 µm. Intraretinal cysts were the most frequent biomarker (78.4%), followed by ellipsoid zone disruption (40.9%), hyperreflective foci (34.1%), DRIL (30.7%), subretinal fluid (21.6%), and external limiting membrane disruption (21.6%). Intraretinal cysts were significantly associated with greater diabetic retinopathy severity (p = 0.025). Conclusions: This study provides a descriptive real-world profile of structural OCT biomarkers in patients with DME attending a tertiary referral center in western Mexico. Intraretinal cysts were the most frequent finding, followed by ellipsoid zone disruption, hyperreflective foci, DRIL, subretinal fluid, and external limiting membrane disruption. These findings provide regional data on the structural characteristics of DME and may serve as comparative evidence for future studies in other populations and clinical settings.