Abstract
Purpose :
Optical coherence tomography (OCT) is a non-invasive, in-vivo imaging technique that enables the cross-sectional examination of retinal layers. This study evaluates the correlation of retinal layer metrics with glycemic control (HbA1c) and visual acuity, in type 2 diabetics. Moreover, the variation in retinal layer metrics between diabetic and non-diabetic patients has also been studied.
Methods :
It is a case control study of 146 patients. Macular cube scan of 512x218 protocol was done to assess central subfield thickness (CST) and average ganglionic cell layer (GCL) - inner plexiform layer(IPL) thickness in an elliptical annulus centered on fovea. Additionally, thickness was measured for inner retina (ILM-OPL) from the internal limiting membrane(ILM) to the proximal boundary of the outer nuclear layer(ONL); outer retina (ONL-RPE) from proximal ONL boundary to the retinal pigment epithelium (RPE); ellipsoid zone(EZ) to RPE(EZ-RPE) and total retina(ILM-RPE) from ILM to RPE at fovea, juxtafoveally at 1 mm nasal and temporal to the fovea. Average retinal nerve fibre layer (RNFL) thickness was evaluated using 200x200 protocol of optic disc cube centered on the optic disc.
Results :
Inner retina including average RNFL thickness, average GCL-IPL thickness, foveal ILM-OPL thickness; EZ-RPE and total retina including juxtafoveal temporal and nasal thickness, showed significant reduction in diabetics. Visual acuity showed weak positive correlation with inner retinal layers. Additionally, total retina juxtafoveal nasal parameter had weak positive correlation with BCVA in diabetics. HbA1C showed weak negative correlation with inner retinal layers. Multivariate regression analysis showed increase in RNFL, GCL-IPL, inner retinal ILM-OPL juxtafoveal temporal and total retinal juxtafoveal nasal thickness were significantly associated with decreased visual acuity.
Conclusions :
With the advent of OCT, quantitative assessment of different retinal layers, could help us detect signs of retinal neuro-degeneration and impending clinical diabetic retinopathy associated with chronic hyperglycaemia. Furthermore, it would serve as a biomarker to detect pre-clinical DR and initiate appropriate clinical interventions.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.