Predictive power of retinal layer responses to intravitreal ranibizumab treatment for diabetic macular edema

Abstract

 

Purpose

 

Indicators forecasting benefit from intravitreal anti vascular endothelial growth factor treatment for diabetic macular edema are lacking. We described the thickness change of individual retinal layers in eyes treated with ranibizumab as per RESOLVE protocol, and investigated the predictive value of individual layer responses on the 1-year (1y) visual acuity outcome.

 

Methods

 

Retrospective interventional case series including 33 eyes of 33 patients. Retinal layers were segmented on high-resolution optical coherence tomography scans (Heidelberg Spectralis^®) at baseline and 1y using automated software (Heidelberg Eye Explorer) with manual correction if needed. Layer thickness changes and other parameters were analyzed using correlation matrices. A model predicting final visual acuity was built using multiple linear regression.

 

Results

 

The only significant layer thickness change was observed in the inner ring for the inner plexiform layer (Image 1). The correlation matrices showed a similar pattern for inner and outer ring of the standard ETDRS grid (Image 2). Thickness changes in the outer plexiform, the outer and the inner nuclear layers were significant factors in the multiple linear regression model predicting 1y visual acuity.

 

Conclusions

 

A differential response of individual retinal layers was observed in diabetic macular edema treated with ranibizumab. Analysis of individual layer responses to initial treatment might be useful to predict treatment benefit. Further prospective studies are needed to determine suitable time points for imaging.  

 

Representative image at A₁) baseline (BL) and A₂) 1 year after treatment initiation (1y). Individual layer thickness for the B₁) inner ring (IR) and B₂) outer ring (OR) of the standard ETDRS grid. [ *< 0.05; t-test]

 

 

Correlation matrix for C₁) inner ring and C₂) outer ring of standard ETDRS grid: Best-corrected visual acuity at 1y (Final_VA), BL (VA_BL) and difference from BL (Diff_VA), number of IVT injections (IVTs), presence of posterior vitreous detachment (PVD), central retina thickness at BL (CRT_BL), decrease of thickness from BL for whole retina (total), ganglion cell layer (GCL), retinal nerve fiber layer (RNFL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL).