Association between Visual Acuity and Retinal Layer Metrics in Diabetic Retinopathy by Enface OCT Imaging

Abstract

Purpose : Diabetic retinopathy (DR) causes alterations in retinal anatomy and progressive visual acuity (VA) loss. The relationship between increased central subfield thickness (CST) and reduced VA is well-established. The purpose of the current study is to identify alterations in individual retinal layer metrics of thickness, reflectance and interface disruption that are associated with reduced VA in DR by enface optical coherence tomography (OCT).

Methods : High density OCT volume scans were acquired in 115 diabetic subjects and best corrected VA (BCVA) was measured. Based on clinical diagnosis, the subjects were grouped as: no diabetic retinopathy (NDR; N=41), non-proliferative DR (NPDR; N=45) and proliferative DR (PDR; N=29; 23 of 29 had pan-retinal photocoagulation). An image segmentation method identified retinal layer interfaces and generated enface thickness maps and reflectance images of nerve fiber layer (NFL), ganglion cell and inner plexiform layer (GCLIPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), photoreceptor outer segment layer (OSL) and retinal pigment epithelium (RPE). Regions with disrupted layer interfaces were marked manually. Retinal layer metrics in the central subfield, including, thickness (CST, NFL_T, GCLIPL_T, INL_T, OPL_T, ONL_T, OSL_T, RPE_T), reflectance ratios relative to RPE (NFL_R, GCLIPL_R, INL_R, OPL_R, ONL_R, OSL_R) and disrupted interface areas relative to the total area (NFL_d, INL_d, ONL_d, RPE_d) were calculated.

Results : BCVA was significantly lower in both NPDR and PDR groups compared to NDR group (P<0.001). CST was significantly higher in NPDR group compared to NDR group (P=0.009) and marginally higher in PDR group compared to NDR group (P=0.06). Increased CST was associated with reduced BCVA (r_s=-0.23, P=0.01), but the associations of reduced BCVA with increased INL_T (r_s=-0.44, P<0.001) and OPL_T (r_s=-0.28, P=0.002) were higher. Furthermore, reduced BCVA had a higher correlation with decreased OSL_R (r_s=0.34, P<0.001) than increased NFL_R (r_s=-0.23, P=0.02) and decreased OSL_T (r_s=0.23, P=0.01). Subjects with disrupted INL and ONL had lower BCVA as compared to subjects without disruptions (P=0.02).

Conclusions : Using enface OCT imaging, alterations in inner and outer retinal layer metrics were identified that may be useful for monitoring visual outcome due to progression and treatment of DR.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.