Changes in Disorganization of Retinal Inner Layers (DRIL) Predict Retinal Sensitivity in Eyes with Diabetic Macular Edema

Abstract

Purpose : To determine whether change in DRIL extent predicts central retinal sensitivity in eyes undergoing therapy for central -involved diabetic macular edema (CIDME).

Methods : Diabetic adults enrolled in a randomized controlled study of ranibizumab vs. macular laser for CIDME. Retinal sensitivity for each ETDRS subfield was determined with microperimetry (Nidek MP1) at 0, 12, 24, and 48 wks. Spectralis spectral domain optical coherence tomography (SDOCT) scans centered on the fovea (120 μm line spacing, 7 scans) were obtained at 0 and 12 wks. Certified, masked graders evaluated each scan for horizontal extent of DRIL caused by blurring of retinal boundaries, cysts, or hyperreflective [HR] foci and for external limiting membrane [ELM] and ellipsoid zone [EZ] disruption within the 1mm foveal zone.

Results : Mean age of 33 participants was 65.7 yrs, diabetes duration was 18.3 yrs, with 12% type 1 and 36% female. Decreases in DRIL from 0-12 wks were associated with improvements in retinal sensitivity in the central 1 mm subfield (point estimate [95% CL]: -0.52 [-0.87, -0.16], p=0.006) and the central 4° (-0.35 [-0.68, -0.20], p=0.04) from 0-12 wks. Conversely, increases in DRIL were related to worsening sensitivity. Decreased DRIL over 12 wks was also predictive of improvement in central subfield sensitivity from 0-24 wks (-0.59 [-0.98, -0.20], p=0.004). Decreased DRIL from 0-12 wks was associated with improvement in central subfield sensitivity from 0-48 wks, but this was not significant. The major contributor to 12 wk change in overall DRIL extent was change in DRIL from cysts (overall DRIL change vs. DRIL change from cysts, r=0.95, p<0.001). In multivariable models including change in SDOCT central subfield thickness, ELM disruption or EZ disruption as possible confounders, the relationship between DRIL change and central subfield sensitivity change over 0-12 and 0-24 wks remained significant.

Conclusions : These findings suggest that DRIL extent within the central foveal zone is correlated with retinal sensitivity in the central subfield. Assessment of early change in DRIL may further allow prediction of future changes in retinal sensitivity. Future studies may elucidate relative contributions of different types of DRIL to its association with visual function.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.