Abstract
Purpose :
To investigate both vascular and neuronal changes in the peripapillary area due to diabetes, using optical coherence tomography angiography (OCT-A).
Methods :
51 eyes of 51 patients affected by non-proliferative diabetic retinopathy (NPDR), and 19 age-matched healthy control eyes were enrolled. NPDR was graded as mild, moderate or severe, according to the International Diabetic Retinopathy and Macular Edema Severity Scale. Each patient underwent full ophthalmologic examination, including best-corrected visual acuity (BCVA), anterior segment biomicroscopy, air puff tonometry, fundus examination, Spectral Domain-OCT with retinal nerve fiber layer (RNFL) thickness analysis and OCT-A. Radial peripapillary capillary plexus (RPCP) was studied using OCT-A. In any OCT-A image larger vessels and optic nerve head were excluded from the vascular analysis and a ring-shaped region of interest (ROI) centered onto the optic nerve head was selected. Vascular Area Density (VAD), Vascular Length Fraction (VLF) and Vascular Diameter Index (VDI) were calculated in the ROI of each OCT-A image, and in any sector of the ROI (superior, nasal, inferior, temporal).
Results :
VAD and VLF were significantly reduced in diabetic patients, compared to control group (p<0.0001 and p=0.0078, respectively), particularly in severe NPDR eyes. This reduction was confirmed analyzing each peripapillary sector (p < 0.05) and was more significant in the inferior sector. VDI was significantly reduced in the NPDR eyes compared to control group (p=0.0018), especially in mild (p=0.0093) and moderate (p=0.0190) NPDR. RNFL thickness decreased in NPDR eyes, without reaching statistical significance (p=0.0766).
Conclusions :
Retinal vascular remodeling due to diabetic retinopathy involves the peripapillary vascularization too, as confirmed by OCT-A quantitative parameters. The different behavior of reduction in perfusion and loss of retinal nerve fibers in the same peripapillary areas suggests that neuronal damage cannot be simply considered secondary to microvascular damage.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.