Purpose: The study aimed to assess the thickness of the ganglion cell–inner plexiform layer (GC–IPL) using spectral-domain optical coherence tomography (SD-OCT) in diabetic patients without retinopathy or with early retinopathy and compare the findings with age- and gender-matched nondiabetic individuals. Methods: The study divided participants into two groups: • First group: Diabetic patients without retinopathy or with mild-to-moderate diabetic retinopathy (DR) without macular edema. • Second group: Age- and sex-matched nondiabetic controls. Posterior pole thickness was measured using Heidelberg Spectralis SD-OCT and compared between the two groups. Results: The study included 30 patients with type 2 diabetes (T2DM) (without retinopathy or with mild-to-moderate non-proliferative diabetic retinopathy) and 30 age- and sex-matched healthy controls. The mean age of participants in both groups was comparable ( P = 0.238). The average inner retinal layer thickness was 220 ± 8.15 μm in the diabetic retinopathy (DR) group and 247.17 ± 16.23 μm in the nondiabetic control group ( P < 0.025). The ganglion cell–inner plexiform layer (GC–IPL) thickness was 76.60 ± 7.65 μm in the DR group and 92.03 ± 6.46 μm in the control group ( P < 0.05). Thus, the average inner retinal layers and GC–IPL thickness were significantly lower in diabetic patients compared with the control population. Conclusion: Type 2 diabetic patients with none or early clinical evidence of retinopathy had lower inner retinal layer thickness when compared with the nondiabetic control group. This study suggests that retinal neurodegeneration precedes the overt microvascular complications of diabetes.
Valakkadavil et al. (Thu,) studied this question.