Comparison of a widefield Polarization-sensitive OCT with standard imaging of Geographic atrophy

Abstract

 

Purpose

 

To image geographic atrophy (GA) with Polarization-sensitive OCT (PS-OCT) and evaluate the data in comparison to standard-imaging methods.

 

Methods

 

51 eyes of 29 patients with unilateral or bilateral GA were imaged with a new widefield PS-OCT system and compared to standard imaging methods like fundus autofluorescence (FAF), red-free imaging (RF) or infrared imaging (IR). The device used in this study is capable of recording 3D datasets of the human retina at a scanning speed of 70.000 A scans/s. Different scanning angles were used ranging from 20x20° up to 40x40°

 

Results

 

Using the widefield PS-OCT, it was possible to reliably demarcate regions of GA. In 33 out of 51 eyes a thickening of the depolarizing area at the retinal pigment epithelium (RPE) was noticed at the GA margins, which corresponded well to regions of hyperautofluorescence in FAF in 26 out of these 33 eyes. An advantage of PS-OCT over AF was that there was no shadowing effect at the fovea, which is caused by the accumulation of pigment in the central macula. Another advantage of PS-OCT over AF-images was the three-dimensional information, making it possible to rule out artefactuous lesions of the retina or the RPE. In the depolarizing material thickness maps not only were the atrophic areas clearly demarcated as hypointense zones (comparable to AF), but also could drusen be observed as hyperintense specks, the signal intensity of which being in contrast to normal RPE (comparable to RF). The absence of RPE in the GA allows a deeper penetration of the imaging beam into the choroid. Therefore choroidal structures can be visualized within the GA comparable to IR-imaging. Additionally, three dimensional intensity-OCT scans provided information of the retinal morphology.

 

Conclusions

 

In eyes with GA, PS-OCT provided comprehensive information of all layers of the ocular fundus (retina, RPE, choroid) in great detail and all locations. Thus, a single three-dimensional PS-OCT dataset provides superior multimodal information as combined AF, IR, RF and standard spectral domain-OCT performed separately.

 

Keywords: 412 age-related macular degeneration • 550 imaging/image analysis: clinical • 701 retinal pigment epithelium