The use of optical coherence tomography angiography and optical coherence tomography to predict visual acuity in diabetic retinopathy

Introduction Diabetic macular ischaemia (DMI) is associated with reduced visual acuity. Limitations exist in assessing the ischaemic component of diabetic retinopathy. Optical coherence tomography angiography (OCTA) is a non-invasive imaging technique to distinguish retinal capillary layers and allow microvascular assessment. Evaluation of DMI is of prognostic significance when planning treatment regimens for diabetic maculopathy. The aims of this study were to evaluate OCTA to assess DMI and correlate findings with structural optical coherence tomography (OCT) features to predict visual acuity. Methods Cross sectional study of fifty-seven eyes ( n = 57) of thirty-seven subjects with diabetic retinopathy. 26/57 (46%) eyes had diabetic macular cysts. OCT and OCTA data from a single visit were analysed. Central retinal thickness, the presence of intraretinal cysts, ellipsoid zone (EZ) disruption, disorganisation of the retinal inner layers (DRIL), foveal avascular zone (FAZ) area, FAZ acircularity, and level of DMI in the superficial capillary plexus were graded according to ETDRS protocols. The deep vascular plexus was also graded for ischaemia. Correlations between measures and visual acuity were explored using regression models. Results Median age was 55 years. Multiple regression analysis showed EZ disruption ( p < 0.05), horizontal DRIL length ( p < 0.01), DMI grade, and FAZ area ( p < 0.1) correlated with visual acuity. Central retinal thickness and the presence of intraretinal cysts did not predict visual acuity in this study. Discussion FAZ area, DMI grade, EZ disruption, and DRIL length correlate with visual acuity and could be incorporated into longitudinal clinical assessment of individual patients with diabetic retinopathy.