Abstract

SO.10.02

Detection and analysis of hard exudates and their precursors by polarization sensitive optical coherence tomography in patients with diabetic maculopathy

Jan Lammer1, Matthias Bolz1, Bernhard Baumann2, Sonja Prager1, Gabor Deak1, Michael Pircher2, Christoph Hitzenberger2, Ursula Schmidt-Erfurth1, DRRG Diabetic Retiopathy Research Group
1Augenheilkunde und Optometrie, Medizinische Universität Wien, Wien, Österreich, 2Medizinische Physik, Medizinische Universität Wien, Wien, Österreich

Objective
Polarization sensitive optical coherence tomography (PS-OCT) is a recently developed technology offering new ways of detecting and analyzing ultrastructural retinal morphology. Aim of this study was to image and analyze hard exudates (HE) and their precursors in patients with diabetic macular edema (DME) by PS-OCT.
Methods
Fifteen consecutive patients with treatment naïve DME were included in the study. During a same day examination, a standardized visual acuity assessment (Early Treatment of Diabetic Retinopathy Study protocol), infrared fundus imaging, color fundus photography and biomicroscopy were performed. Additionally, all patients were scanned using Stratus™, Cirrus™ (Carl Zeiss, Meditec) and Spectralis™ (Heidelberg Engineering) OCT. Furthermore a prototype PS-OCT device was used allowing raster scanning of the retina in order to detect, map and measure HE and their precursors due to their certain polarization scrambling qualities. Images of all devices were compared regarding presence and appearance of HE.
Results
In all examined eyes HE were present due to DME. In the intensity based OCT images (Stratus™, Cirrus™, Spectralis™ OCT and intensity images of PS-OCT) HE were identified as hyper reflective particles at the border of the outer plexiform and in the inner nuclear layer in accordance to the localization in colour fundus photography but precursors were also found in layers above close to microaneurisms and the cystoid emeda. When analyzing the polarization sensitive data, the HE showed polarization scrambling characteristics similar to what has recently been described for the retinal pigment epithelium (RPE).
Conclusions
In this study HE and their precursors were firstly examined by PS-OCT and identified as particles with polarization scrambling qualities. This finding enables not only to quantify the extension of the HE in two dimensions (as by colour fundus photography) but also in three dimensions and to quantify the amount of intra-retinal lipid exudation.

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