Impact of high myopia on inner retinal layer thickness in type 2 diabetes patients

To investigate the impact of the combination of type 2 diabetes (DM) and high myopia on inner retinal layer thickness of the macular area. The patients were divided into four groups: control (group 1), patients with DM without high myopia (group 2), patients with high myopia without DM (group 3), and patients with DM and high myopia (group 4). Ganglion cell complex (GCC) thickness was compared among the groups. Linear regression analysis was performed to identify factors associated with GCC thickness. A total of 194 eyes were enrolled: 59 in group 1, 52 in group 2, 49 in group 3, and 34 in group 4. The average parafovea GCC thicknesses were 113.9 ± 10.4, 112.4 ± 11.2, 112.2 ± 7.8, and 102.6 ± 15.1 μm (P < 0.001), and the average perifovea GCC thicknesses were 104.8 ± 13.2, 103.5 ± 10.8, 103.6 ± 8.8, and 93.9 ± 15.5 μm in groups 1, 2, 3 and 4, respectively (P = 0.001). In multivariate analyses, age (β = − 0.20, P = 0.007), DM duration (β = − 0.34, P = 0.023), and axial length (β = − 1.64, P < 0.001) were significantly associated with parafoveal GCC thickness. The GCC was significantly thinner when high myopia and DM were combined, compared to either condition alone. Additionally, age, DM duration, and axial length were significant factors associated with GCC thickness. The combination of mechanical stretching and neurodegeneration would accelerate neural damage to the retina, resulting in greater inner retinal layer thinning.