Abstract
Purpose :
The understanding of retinal pathophysiology and its relationship with visual function in the early stage of diabetic retinopathy (DR) is currently limited, which may be partly explained by the recent finding that different pathways get involved in initial stages of DR. We aim to investigate the association between different disease pathways and best corrected visual acuity (BCVA) in eyes with early stages of DR in a multimodal imaging method.
Methods :
The cohort included 109 eyes from 80 diabetic patients with nonproliferative diabetic retinopathy (NPDR) without any previous treatment. Structural optical coherence tomography (OCT) and OCT angiography (OCTA) data were analyzed. Vessel density (VD), the area of foveal avascular zone (FAZ), volumetric vessel density (VVD) and intraretinal layer thickness were measured, and BCVA was recorded. Neurodegeneration was identified by thinning of the retinal nerve fiber layer (RNFL) and/or ganglion cell layer (GCL). Edema was identified by thickening of the inner nuclear layer (INL), outer plexiform layer (OPL), Henle fiber layer and outer nuclear layer (HFL+ONL) or full retina. Ischemia was identified by metrics of retinal vessel density and area of FAZ. The VVD of the macula was calculated as the VD divided by the corresponding tissue volume, which combines the alteration of microvascular and microstructure. Correlations between BCVA and VD, FAZ, VVD and thickness of the sublayers were determined. Eyes were classified into 2 groups according to BCVA: normal (logMAR, 0; Snellen equivalent, 20/20) and decreased (logMAR, >0; Snellen equivalent, <20/20).
Results :
Comparing to the eyes with DR and normal VA, eyes with decreased VA showed significant lower mean vessel density in deep capillary plexus (DCP) (p=0.003), lower VVD in DCP (p=0.006) and increased thickness of Henle fiber layer and outer nuclear layer (HFL+ONL) (p=0.036). Univariate and multiple regression analysis showed that the VVD in DCP was significantly correlated with BCVA in DR (all p<0.05).
Conclusions :
The ischemia and edema may act as primary roles in the early visual impairment in DR patients. The decrease of volumetric vessel density in deep capillary plexus is significantly correlated with BCVA in eyes with early stages of DR. This parameter may improve our understanding of pathophysiologic mechanisms and anatomic correlates for visual loss.
This is a 2020 ARVO Annual Meeting abstract.