Retinal Layers Changes in Diabetic Patients without Diabetic Retinopathy

Abstract

PurposeTo evaluate retinal layers thickness in diabetic patients without diabetic retinopathy (DR) using spectral‐domain optical coherence tomography (SD‐OCT). To correlate retinal layers thickness in diabetic patients with disease duration, systemic blood pressure (BP), glycemia, glycosylate haemoglobin (HbA1c), intraocular pressure (IOP) and ocular pulse amplitude (OPA).MethodsProspective, observational case–control study. A total of 175 eyes from 175 patients (125 diabetic patients without DR; 50 healthy controls) were recruited from the outpatient clinic in a tertiary center. A complete ophthalmological examination was performed (visual acuity, refraction, Goldmann applanation and dynamic contour tonometries, fundoscopy, axial length and SD‐OCT‐Spectralis®). After automated retinal segmentation the thickness of each layer was calculated in the 9 ETDRS areas.ResultsA significant increase of retinal nerve fiber layer (RNFL) thickness in inner and outer rings was found in diabetic eyes vs. controls (p between <0.0001 and 0.02). Thickness was also increased in specific sites of ganglion cell layer (GCL), inner nuclear layer (INL) and retinal pigment epithelium (RPE) in diabetic eyes (p between 0.001 and 0.03). A significant decrease of outer plexiform layer (OPL) was detected in diabetic eyes at two sites of the inner ring (p = 0.04 and p < 0.0001). The different retinal layers weren't correlated with systemic BP, glycemia, HbA1c, IOP and OPA, but the photoreceptor layer was negatively correlated with disease duration at 3 sites (r between −0.18 and −0.21, p < 0.05).ConclusionsIn diabetic patients without DR thickness of the inner retina seems to be increased. This suggests that metabolic and morphological changes of the cells of these inner retinal layers occur early and before the apoptosis and neural degeneration.