Drusen volume progression and the Development of neovascular Age-related Macular Degeneration

Abstract

 

Purpose

 

To identify the pathway from drusen progression to the development of advanced age-related macular degeneration (AMD).

 

Methods

 

Patients with early AMD were imaged using simultaneous spectral-domain (SD-OCT, Spectralis) and polarization-sensitive OCT (PS-OCT). All patients underwent continuous follow-up examinations every 6 months for three years. Data obtained with PS-OCT were segmented for drusen volume automatically using an algorithm based on the RPE-based polarization-sensitive information, whereas SD-OCT data were segmented manually by expert graders using an OCT-reader software (OCTAVO).

 

Results

 

104 patients were enclosed in the study. Out of this group, 56 eyes with very good scanning quality and continuous follow-up visits were selected for manual grading. In total, more than 32000 individual B-scans were graded and compared to the results of the automated segmentation done by PS-OCT. The mean drusen volume per eye at baseline was 0.12mm3 for SD-OCT and 0.15mm3 for PS-OCT. The increase of drusen volume over time was shown to be approximately linear, with a regression equation of y=0.028x + 1.0 for SD-OCT and y=0.029x + 1.0 for PS-OCT (x = months), with a calculated doubling of drusen volume after 35.1 resp. 34.2 months. Drusen regression was observed in 28 eyes at least once over three years. Of this group, 8 eyes developed choroidal neovascularization (CNV) and 2 eyes geographic atrophy. Eyes without drusen regression showed no signs of progression towards advanced AMD.

 

Conclusions

 

Drusen showed a linear increase in volume over time. A spontaneous regression without signs of advanced AMD occurred quite often. However, the development of advanced AMD was announced by a regression of drusen volume. Therefore, OCT showed to be a promising tool for predicting the individual risk for progression of AMD.

 

 

Keywords: 504 drusen • 412 age-related macular degeneration • 550 imaging/image analysis: clinical