Retinal Perifoveal Inner Layer Disorganization as a Predictor of Visual Acuity Outcomes in Eyes with Center-involved Diabetic Macular Edema

Abstract

Purpose: To assess parameters on spectral domain optical coherence tomography (SDOCT) that may better correlate with visual acuity (VA) outcomes than central subfield thickness (CST) in eyes with center-involved DME (ciDME).

Methods: Patients with ciDME underwent ETDRS VA testing and SDOCT imaging on Spectralis (20x20°, 49 b scans, 16 ART Mean, high res setting) at baseline and 8 months. The central 1mm area on 7 b scans centered on the fovea was graded in masked fashion to evaluate presence, location and extent of retinal perifoveal inner layer disorganization (PILD: inability to distinguish boundaries between any of the inner retinal layers), hyperreflective foci, cysts, subretinal fluid, epiretinal membranes (ERM), and external limiting membrane (ELM) or inner segment-outer segment junction (ISOS) disruption.

Results: 24 eyes of 19 patients were evaluated. Baseline mean±SD logmar VA was 0.33±0.30, and CST was 423±122µm. Mean age was 61±15 years, diabetes duration 25±14 years, 47% were male and 37% type 1 DM. Eyes with better baseline VA had fewer OCT lines affected by PILD (2.8±2.8 vs. 4.0±2.1), although this and all other OCT variables did not reach statistical significance in relation to baseline VA. Over 8 months follow-up, 20 eyes (83%) received intravitreal anti-VEGF and 1 (4%) macular laser treatment for ciDME. Mean CST decreased by 92±108µm, and logmar VA improved by 0.07±0.13. In unadjusted analyses, improvement in VA was associated with worse baseline VA (improved VA vs unimproved VA: 0.45±0.27 vs 0.16±0.10, respectively, p=0.002), higher percentage of baseline b scans with PILD (57±29% vs 43±29%, p=0.03) and greater decrease in PILD (291±250µm vs 115±129µm, p=0.02), but not to other baseline OCT values or changes in the variables over time. In a multivariate model adjusting for baseline VA, VA improvement remained significantly associated with PILD decreases (1 mm decrease in PILD = 2 line VA improvement, p=0.03).

Conclusions: In eyes with ciDME, change in PILD over time is more closely related to VA outcomes than either CST or disruption of outer layer structures including the ELM and ISOS junction. If validated in larger prospective studies, these findings suggest that PILD may serve as a readily measured surrogate biomarker for VA and help predict functional response to ciDME treatment over time.

Keywords: 505 edema • 550 imaging/image analysis: clinical • 499 diabetic retinopathy