Severity of Disorganization of Retinal Layers and Visual Function Impairment in Diabetic Retinopathy

Purpose To evaluate best corrected visual acuity (BCVA), retina sensitivity (RS) and fixation impairment by microperimetry (MP) due to the presence and severity of disorganization of inner and outer retinal layers (DRIL/DROL) and ischemia in OCT/OCT-Angiography(OCT-A) in diabetic retinopathy (DR). Design Retrospective case-control study. Subjects Seventy-six eyes (65 patients) with DR were analyzed. Major exclusion criteria were: center-involving diabetic macular edema (DME), significant media opacity, nondiabetic macular pathology, active proliferative DR. Patients with DRIL and DROL within central 3 mm were enrolled as cases. Patients with DR and no retina disorganization were considered as controls. Methods A detailed grading of microperimetry and OCT/OCT-A images using Image J software, and specific Image Manipulation Program was applied to co-localize the presence of retina disorganization and RS. BCVA and RS were correlated with the disorganization of retina layers’ characteristics and grading (Grade 1-DRIL; Grade 2-DROL; Grade 3-DROL plus, with involvement of the ellipsoid zone). The same procedure of co-localization was applied to the vascular layers on OCT-A using Matlab. Main Outcome Correlation between BCVA and microperimetry parameters with disorganization of retina layers grading and OCT-A parameters. Results BCVA, mean RS within 1mm and central 3mm (overall RS-oRS), perfusion density, vessel density and geometric perfusion deficit in intermediate and deep capillary plexuses were lower in cases versus controls (p<.001). Mean RS within 1mm (21.4dB±2.4 vs 13.8dB±5.4, p=.002), oRS (22.0dB±2.1 vs 14.4dB ±4.6, p<.001), and BCVA (76.1±7.4 vs 61.2±20.4 ETDRS letters; p=.02), had a significant decrease from grade 1 to grade 3 retina disorganization.Choriocapillaris flow-voids (CC-FV) increased from grade 1 to grade 3 (DROL plus) (p=.004). oRS and CC-FV were identified as significant predictors of retina disorganization grade with an adjusted coefficient of determination, R2=0.45. Cases had more dense scotomas(p=.03) than controls with a positive correlation between the worsening of fixation stability and the severity of DRIL/DROL(p=.04). Conclusion MP and BCVA documented a reduction in visual function in patients with DR and disorganization of retina layers at different grades, with greater functional impairment when outer retina layers and photoreceptors are involved. The severity of retina disorganization and the presence of ischemia could serve as a potential biomarker of functional impairment.