Comparison of the Effects of Anti-VEGF Therapy on Retinal Vessel Caliber (RVC) in Eyes with NV-AMD

Abstract

 

Purpose

 

Previous studies have shown the effect of anti-VEGF therapy on RVC. The current study compares changes in RVC in macular area of eyes with NV-AMD treated with IVT injections of aflibercept (AFL) or ranibizumab (RBZ) using Heidelberg Eye Explorer (HEYEX v5.6) measurement tool.

 

Methods

 

In this retrospective study, a novel technique employs HEYEX to measure manually the RVC. Images of patients with NV-AMD treated at a tertiary care center from 07/2013 to 07/2014 were reviewed & analyzed. Patients were categorized into two groups: (1) treated with AFL & (2) treated with RBZ. Patients who received 4 consecutive IVT injections of either RBZ or AFL & had cSLO images of sufficient quality for analysis at baseline (BL) & endpoint (EP) were included. Patients with associated hemorrhage or severe macular scarring were excluded. 30° cSLO images of the 2M Field acquired with Heidelberg Spectralis® were analyzed. Using HEYEX, calibers of largest arteriole & largest venule coursing through a circumferential area 0.5 -1.0 disc diameter from the foveal center (Zone B; Figure) were manually measured at BL & EP. Data was reported as macular retinal arteriolar equivalent (MRAE) & macular retinal venular equivalent (MRVE). Changes of MRAE & MRVE were compared between BL & EP for the two treatment groups. MRAE & MRVE produced by HEYEX were also correlated to MRAE & MRVE of the same arteriole & venule produced by modified interactive vessel analysis software (m-IVAN) for method validation.

 

Results

 

Ten eyes (10 patients) treated with AFL & 10 eyes (9 patients) treated with RBZ met the inclusion criteria. Mean ages were 75 & 80 years for AFL & RBZ groups, respectively. Summary of results is represented in the Table. MRAE & MRVE measured by Heyex showed strong correlation to MRAE & MRVE measured by m-IVAN (r=0.95).

 

Conclusions

 

In this small cohort, repeated IVT injections of AFL resulted in statistically significant (p < 0.05) narrowing of macular arterioles in eyes with NV-AMD. No statistically significant narrowing of arterioles was noted with RBZ injections. In addition, no statistically significant narrowing or enlargement of macular venules was seen with either AFL or RBZ injections.  

 

Calibers of arterioles (red arrowheads) & venules (blue arrowheads) in zone B, 0.5 - 1.0 disc diameter from foveal center, were measured by m-IVAN software (A) and Heyex software (B).<br />

 

 

Summary of Results.