Longitudinal Quantitative OCT Analysis of Drusen in the Fellow Eye of Patients with Unilateral Neovascular Age-Related Macular Degeneration

Abstract

 

Purpose

 

The fellow eyes of patients with late AMD in one eye may be at the highest risk of developing late AMD. Reduction of drusen volume without the development of late AMD has been suggested as a potential therapeutic endpoint in early intervention trials. To determine the relationship between drusen volume and late AMD, we evaluated longitudinal changes in the fellow eye of patients with unilateral neovascular AMD using optical coherence tomography (OCT).

 

Methods

 

In this retrospective analysis, we analyzed the fellow eye of 42 patients (age range, 69-93 years) who had advanced neovascular AMD in only 1 eye. All patients were treated with intravitreal ranibizumab, pegaptanib, or/and bevacizumab and followed up for two years. In this analysis, we focused on the fellow eye with only evidence of drusen secondary to the non-exudative AMD. All eyes were scanned with the Cirrus HD-OCT (Carl Zeiss Meditec, Inc., Dublin, CA) using a 512 ×128 scan pattern. OCT data at baseline, Month 12, and Month 24 was evaluated using the advanced RPE analysis tool to quantify drusen volume within 3mm and 5mm diameter circles. OCT scans were also evaluated for the development of atrophy or CNV.

 

Results

 

Drusen without evidence of late AMD were evident in 18 participants (42.9%). After 12 months, none of the eyes developed neovascular disease but two eyes (11.1%) developed geographic atrophy (GA). By 24 months of follow-up, 4 eyes (22.2%) developed GA and no eyes developed CNV. Once the eye progressed to GA it was censored from the quantitative drusen study. After two years, there were no statistically significant changes in drusen area or volume for the cohort overall. There was also no statistically significant (p = 0.38, in 3mm; p=0.10, in 5mm) difference in baseline drusen volume between eyes which developed atrophy compared with those that did not. However, in eyes which developed atrophy by Month 24, drusen volume had decreased at Month 12 by 0.06 ± 0.06 mm³ compared with 0.01 ± 0.04 mm³ in eyes without atrophy.

 

Conclusions

 

Changes in drusen volume and development of GA can be tracked using SDOCT. Although baseline drusen volume did not appear to predict atrophy development, a decrease in drusen volume was associated with new atrophy. This suggests the potential for drusen volume changes to be used as biomarkers to identify eyes at high risk for progression to atrophy.