Abstract
Purpose :
To evaluate the impact of switching to ranibizumab in bevacizumab-resistant diabetic macular edema (DME) on quantitative metrics in multiple imaging modalities and potential imaging biomarkers
Methods :
REACT is an IRB-approved 12-month, prospective IND trial evaluating efficacy of ranibizumab in eyes with bevacizumab-resistant DME. Ultra-widefield fluorescein angiography (UWFA) images (Optos 200Tx, Optos) were obtained at baseline, month 3, 6, and 12. Early and late-phase FA images were analyzed with an automated platform to quantify microaneurysm (MA) counts and leakage burden. OCT images at baseline and study exit were evaluated with an automated software system for ellipsoid zone mapping and volumetric fluid assessment. Each B-scan was manually reviewed for segmentation accuracy. Quantitative OCT metrics evaluated included intraretinal fluid (IRF) volume and ellipsoid zone to retinal pigment epithelium volume (EZ-RPE).
Results :
Twenty-seven subjects were enrolled in the REACT study. In eyes showing visual acuity (VA) improvement, there was a significant reduction in leakage area at study exit compared to baseline (p=0.046). In contrast, eyes without VA gain demonstrated no change in leakage burden (p=0.742). Decreased MA counts were observed independent of VA at each time point compared to baseline (p=0.015). For volumetric OCT assessment, eyes with VA improvement demonstrated significant reductions in IRF volume at study end compared to baseline (p =0.001) and stability of the EZ-RPE. In contrast, eyes without functional improvement revealed no change in IRF volume at study exit and degradation of the EZ-RPE (p=0.037).
Conclusions :
Quantitative UWFA demonstrates underlying retinal vascular alterations following switching to ranibizumab in treatment-resistant eyes, including reduction in MA in counts. In eyes with functional improvement, a significant reduction in leakage area was also noted. Similarly a differential response in anatomic metrics was noted with OCT. Additional research is needed to better define the role of these quantitative parameters in disease management and the potential implication for these features as imaging biomarkers.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.