Analysis of partial and complete sparing of the Fovea in patients with Geograpic Atrophy by Polarization-Sensitive Optical Coherence Tomography

Abstract

 

Purpose

 

To analyze the relation of partial and complete foveal sparing in patients with geographic atrophy (GA) using retinal imaging devices and visual acuity.

 

Methods

 

46 eyes of 27 consecutive patients with GA were imaged with the Spectralis HRA+OCT (Heidelberg Engineering) and a new wide-field PS-OCT system recording 3D datasets of the human retina at a scanning speed of 70.000 A scans/s and a scanning angle of up to 40° x 40°. Best-corrected visual acuity (BCVA) obtained prior to novel and conventional retinal imaging consisting in Spectral-Domain OCT (SD-OCT), fundus autofluorescence (FAF) and infrared imaging (IR) was used after the analysis of the foveal status in these imaging devices in order to detect the plausibility of the results.

 

Results

 

In 20 eyes the fovea could be identified as definitely involved in the GA process among all imaging devices. Mean BCVA in this group was 20/100 Snellen equivalent (SE). In one eye SD and PS-OCT showed an area of spared RPE but with choroidal signal enhancement underneath this RPE-island. However PS-OCT revealed depolarizing properties at the level of the RPE. BCVA was 20/80 SE. In 25 eyes (mean BCVA = 20/43 SE) SD-OCT and PS-OCT revealed either foveal sparing or RPE spared islands in the fovea which could only partially be detected in 8 eyes in FAF and IR imaging simultaneously analyzed (mean BCVA = 20/60 SE) and in 6 eyes when graded in FAF alone (mean BCVA = 20/80 SE).

 

Conclusions

 

Novel imaging modalities such as PS-OCT allowing simultaneously insights into morphological and functional features of the retina such as into the RPE layer are valuable if future treatment options are to be designed and evaluated. The sensitivity and specificity for detecting patients gaining from treatment options or considering treatment success itself can be increased and is therefore valuable for future clinical trials in this field of research.

 

Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • 412 age-related macular degeneration