Abstract
Purpose:
to evaluate the thickness of outer and inner retinal layers in cross-section SD-OCT images and multifocal electroretinograms (mfERG) of patients with type 1 diabetes mellitus with no signs (noDR) or mild non proliferative diabetic retinopathy (NPDR)
Methods:
Sixty-four patients with type 1 diabetes (DM1) were recruited in the study; 32 of these had noDR and 32 had NPDR. 16 healthy subjects were recruited as controls. Manual segmentation of retinal cross-sections in SD-OCT images included the Outer Retinal Thickness (ORT, from Outer plexiform layer to retinal pigment epithelium ), the Inner Retinal Thickness (IRT, from Inner limiting membrane to Inner plexiform layer ), the Subfoveal Retinal Thickness (SRT) and cone outer segment tips (COST). The MfERG N1-P1 response amplitude densities (RADs) were recorded in each cases.
Results:
DM1 duration was 13.5± 0.7 years in noDR and 23.5 ± 14.84 years in NPDR; HbA1c was 7.7±1 % in noDR and 7.5 ±1.3 % in NPDR. The mean ORT thickness was 170±17 in noDR, 167±16 in NPDR and 163±11 μm in control eyes; the mean IRT was 86±21, 94±22 and 87± 23μm respectively. The mean SRT was 209± 37, 202±17 and 161.69 ± 34.3 μm respectively; while the COST was 18.4±4.36, 14.8±5.14 and 22.5±4.3 μm respectively. The mfERG N1-P1 RADs across the central ring was 77±29 nV/deg2 in noDR, 78±28 nV/deg2 in NPDR eyes and 84±30 nV/deg2 in controls.
Conclusions:
A combined study of the structure and function of photoreceptors and bipolar cells in cross-section SD-OCT images and mfERG recordings may represent a valuable approach to identify neurodegeneration process caused by DM1.