Assessing diabetic macular edema through spectral domain optical coherence tomography: an analysis of foveal thickness, external limiting membrane, and ellipsoid zone integrity

Background and Aim: This study emphasizes using external limiting membrane (ELM) and EZ ellipsoid zone (EZ), disruption as imaging biomarkers in fovea-involved diabetic macular edema (DME). Materials and Methods: This is a retrospective study conducted in the Department of Ophthalmology, Gitam Institute of Medical Sciences and Research, from June 2021 to May 2022. Spectral-domain optical coherence tomography (SD-OCT) images of 17 patients with fovea-involved DME were analyzed in this retrospective pilot study. Neither disruption of ELM nor EZ was graded 0, only disruption of ELM was graded as 1, and disruptions of both ELM and EZ were graded 2. Results: Twenty-five eyes (SD-OCT pictures) of 17 patients, nine men and eight women, with a mean age of 54.23 years (35–77 years), were included in the study. Eleven (44%) eyes had mild nonproliferative diabetic retinopathy (NDPR) with clinically significant macular edema (CSME). Seven (28%) eyes had moderate nonproliferative diabetic retinopathy (NPDR) with CSME, and 7 (28%) eyes had severe NPDR with CSME. Cystoid pattern of macular edema was present in 15 (60%) eyes; 3 (12%) eyes had cystoid pattern with vitreomacular traction (VMT), 1 (4%) eye had cystoid pattern with serous retinal detachment (RD), 5 (20%) eyes had diffuse macular edema, and 1 (4%) eye had diffuse CSME with VMT. Ten (40%) eyes had grade 0 ELM and EZ disruption with a foveal thickness of 245–310 μ (mean – 269.2), 3 (12%) eyes had grade 1 with foveal thickness varying from 263 to 348 μ (mean 301.3) and 12 (48%) eyes had grade 2 with a macular thickness of 315–651 μ (mean 467.8). Conclusion: A statistically significant association exists between foveal thickness and disruption of the ELM and EZ. Grade 0 had a foveal thickness ranging from 240 to 260 μ, grade 1 from 260 to 340 μ, and grade 2 from 340-≤650 μ.