Associations of quantitative contrast sensitivity with vascular metrics on widefield swept-source OCT angiography across stages of diabetic retinopathy

Purpose To investigate structure-function associations between contrast sensitivity (CS) and widefield swept-source optical coherence tomography angiography (WF SS-OCTA) vascular metrics across stages of non-proliferative (NPDR) and proliferative diabetic retinopathy (PDR), without diabetic macular oedema. Methods Prospective cross-sectional study in 140 eyes of 99 patients: 33 mild NPDR, 24 moderate/severe NPDR, 15 PDR, 33 diabetic without DR (DMnoDR) and 46 control eyes. Mixed-effects multivariable regression models to evaluate associations between quantitative contrast sensitivity function (Adaptive Sensory Technology) and vessel density (VD) and vessel skeletonised density (VSD) in the superficial capillary plexus (SCP) and deep capillary plexus (DCP) on same-day imaging with WF SS-OCTA (Plex Elite 9000, Carl Zeiss Meditec). Results Standardised beta coefficients for area under the logarithm of contrast sensitivity function curve (AULCSF) versus visual acuity (VA) at 3x3 mm scans: SCP VSD (beta=0.32, p<0.001 vs -0.18, p=0.044), DCP VSD (beta=0.30, p<0.001 vs -0.21, p=0.02), SCP VD (beta=0.25, p=0.004 vs -0.13, p=0.129), DCP VD (beta=0.26, p=0.003 vs -0.19, p=0.034). AULCSF was significantly reduced in mild NPDR (beta=-0.28, p<0.001) and DMnoDR (beta=-0.19, p=0.005) versus controls, while VA was not significantly different. AULCSF performed better than VA in differentiating between controls and DMnoDR (0.69 vs 0.50), controls and mild NPDR (0.76 vs 0.61) and controls and moderate/severe NPDR (0.89 vs 0.73). Conclusions DR-induced microvascular changes on OCTA are associated with larger changes on CS than in VA. CS is affected earlier than VA in the course of DR and performed better in discriminating between controls, DMnoDR and across DR stages.