Abstract

SA.23.02

Evaluation of geographic atrophy through autofluorescence and optical cohrence tomography

Ramzi Gilbert Sayegh1, Christian Simader1, Christian Prünte1, Christoph K. Hitzenberger2, Julia Schumann1, Christopher Schütze1, Ursula Schmidt-Erfurth1
1Universitätsklinik für Ophtalmologie und Optometrie, Medizinische Universität Wien, Wien, Österreich, 2Zentrum für Biomedizinische Technik und Physik, Medizinische Physik, Wien, Österreich

Objective
Autofluorescence (AF) enables through two-dimensional “en face” imaging technique to visualize geographic atrophy (GA) in patients with age related macula degeneration (ARMD) and to predict the progress of this disease in the retina. The currently available three-dimensional optical coherence tomography (SD-OCT) methods allow not only to qualitatively evaluate the clinical picture of the retina but also to quantitatively grade morphological structure changes in the cross section and the “en face” scans. The aim of the study is to compare both imaging techniques regarding geographic atrophy and to measure the corresponding atrophic areas.
Methods
40 eyes of 40 patients showing vision loss only caused by GA in ARMD have been included in a prospective study with 3 month follow up visits and were thereafter analyzed.
At each visit AF and a series of SD-OCT images with different tools, Spectralis® OCT (Heidelberg Engineering), Cirrus® OCT (Carl Zeiss Meditec) and a Polarisation sensitive OCT (PS-OCT), were captured. The PS-OCT enables in addition to both other OCT modalities to visualize furthermore depolarization sensitive tissue such as retinal pigment epithelium (RPE) and to therefore differentiate tissue structures. Those imaging modalities were then qualitatively and quantitatively graded and compared by 4 different graders.
Results
Morphologically all imaging modalities could define areas with central RPE loss. The 3 dimensional SD-OCT methods not only allowed visualization of the RPE loss through acoustic shadowing but also through representation and measurement of the atrophic neurosensory retina in the B-scans. Reproducible qualitative differences to vital retinas could be illustrated and then quantitatively compared to AF results.
Conclusions
The 3 SD-OCT systems used in this study showed similar results in matters of retinal thickness values and can moreover be used to evaluate the atrophic area as in AF. The lesion areas measured in all imaging methods showed similar results and therefore the possibility of morphological grading through the SD-OCT B-scan seem to have more advantages.

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