Retinal Layer Thickness in Drusen and Drusen-Free Retinal Areas in Age-Related Macular Degeneration.

Abstract

Purpose: Drusen are a hallmark of age-related macular degeneration (AMD). However how drusen affect retinal structure at and beyond their borders is still unclear. This study examines changes in retinal thickness which occurs above drusen and compares this to drusen-free areas in the same patient and a normative population.

Methods: Spectral domain optical coherence tomography scans through drusen in early to intermediate AMD patients (n=122) or patients with no ocular disease (n=30) seen at the Centre for Eye Health were reviewed and the thickness of individual retinal layers was measured above the druse and in a drusen-free area, 150µm from the drusen edge. Patient written consent was obtained in accordance with the Declaration of Helsinki and approved by the Biomedical Human Research Ethics Advisory Panel of the University of New South Wales.

Results: Retinal thickness above drusen was significantly less (p < 0.001) than drusen-free areas (16±1%). Thinning occurred almost exclusively in the outer retinal layers with almost no thinning in the inner retina for single isolated drusen. Inner retinal thickness was however reduced over large confluent drusen (5±1%). Interestingly, the overall retinal thickness of both drusen and drusen-free areas was significantly less to matching eccentricities in the normal population.

Conclusions: Drusen caused retinal thinning, mostly by affecting the outer retina. Drusen-free areas in AMD patients were also thinned suggesting the effects of drusen extend beyond the lesion borders. This has implications in the use of presumably “normal” areas of retina in AMD patients for disease assessment.