Changes in the Outer Retinal Layers in Patients With Drusen Using SD-OCT (Spectralis*)

Abstract

Purpose: : Spectral Domain OCT imaging enables a high resolution analysis of retinal layers.The aim of this study was to analyse the morphologic changes in the outer retinal layers of 50 consecutive patients presenting with different type of drusen using the high resolution Spectral Domain OCT imaging.

Methods: : 50 consecutive patients presenting with drusen were evaluated and followed by slit lamp biomicroscopy, fluorescein and indocyanine green (ICGA-SLO) angiographies and SD-OCT (Spectralis* Heidelberg) examinations.Fifty subgroups of drusen were separately analyzed: 1-Hard drusen, (6%) , 2- soft drusen, (16%,), 3-soft confluent drusen (4%) 4- both soft and hard drusen (72%) 5- Soft, and hard drusen associated with Drusenoid RPE detachment (4%),Morphologic changes in outer retinal layers (outer nuclear layer, external limiting membrane ELM, IS/OS interface, RPE, Bruch’s membrane) and the characteristics of the lesions were evaluated.

Results: : For the hard drusen subgroup- the BM was not visible, the drusen were hyper-reflective and homogenous (100%) the IS/OS interface was continuous (100%) smooth(41%),elevated (100%); the ELM was continuous(100%) and elevated (72%) . the outer nuclear layer was intact (100%) but with jagged edges(60%) %.Soft drusen- the BM was visible and separated from RPE layer in 100%; the content was inhomogeneous (100%) either punctuate(84%), or fibrillar (6%) with hypo and hyper reflectivity(100%) the IS/OS interface was continuous in 22% fragmented (76%) , uneven in 93%, hyporeflective in 80% and elevated in 100%. The ELM was elevated and often fragmented (40%). The outer nuclear layer was almost always thin (90%), with jagged edges (95%). For Confluent drusen and drusenoid PED- the IS/OS interface was fragmented in most of the cases (80%), always hyporeflective in the drusenoid PED and in 40% of the confluent drusen and always elevated. The ELM was continuous in (80%) of cases of confluent drusen but fragmented in the drusenoid PED.

Conclusions: : The different structures of drusen and the changes in outer retinal layers were demonstrated by the SD OCT. A correlation between SD-OCT images and histologic findings was found.

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