Assessment of the retinal ganglion cell complex using optical coherence tomography in patients with diabetes mellitus without diabetic retinopathy: results of a study conducted under martial law

Objective: to assess the thickness of the retinal ganglion cell complex (GCC) in patients with type 2 diabetes mellitus (T2DM) without signs of diabetic retinopathy (DR) and to determine the diagnostic performance of sectoral GCC parameters using ROC analysis in patients examined under conditions of prolonged martial law. Materials and methods. A prospective study of the retinal GCC was conducted in patients with T2DM without clinical signs of DR (25 patients, 50 eyes) and compared with a control group of healthy individuals (20 participants, 40 eyes). The mean age of patients with T2DM was 50.8±11.1 years, and the mean duration of diabetes was 8.23±6.38 years. All participants underwent a standard ophthalmological examination and optical coherence tomography (OCT) using the «Optovue RTVue XR Avanti» system («Optovue Inc.», USA). GCC parameters were analyzed in the parafoveal and perifoveal regions according to the automated Angio Retina analysis protocol. Statistical analysis was performed using methods of descriptive and inferential statistics in Jamovi version 2.7. ROC analysis was performed to assess the diagnostic performance of GCC measurements in individual sectors. Results. Patients with T2DM without clinical manifestations of DR demonstrated a significant reduction in GCC thickness compared with the control group. The most pronounced statistically significant changes were observed in the superior, inferior, nasal, and temporal sectors of the parafoveal region (p≤0.05), whereas in the perifoveal region, statistically significant thinning was detected only in the nasal sector. ROC analysis demonstrated moderate diagnostic performance of the sectoral GCC parameters, with the highest areas under the ROC curve observed for the inferior (AUC=0.663) and superior (AUC=0.644) sectors of the parafoveal region. Conclusions. Early assessment of the GCC using OCT may represent a promising approach for detecting retinal neurodegeneration at the preclinical stage of DR. Sectoral GCC parameters in the parafoveal region demonstrated the greatest diagnostic value. These findings may facilitate the identification of patients at increased risk of subsequent DR development and may be useful for monitoring the progression of this complication of diabetes mellitus.