Longitudinal Lesion Size Detection of Geographic Atrophy using Polarisation-Sensitive and Spectral-Domain Optical Coherence Tomography in comparison to Fundus Autofluorescence

Abstract

 

Purpose:

 

As currently no therapeutical intervention in dry age related macular degeneration (AMD) is possible, imaging of this disease and the disease progression in an exact manner is mandatory if scientific progress is to be obtained. Furthermore lesion size determination in the natural history of geographic atrophy (GA) has gained acceptance as an endpoint parameter in clinical trials in targeting dry AMD and this underlines the importance of comparing different retinal imaging modalities which each other.

 

Methods:

 

For that purpose we analyzed 20 eyes of 20 patients with GA in a follow up manner with visits at baseline, month, 6 and 12. Retinal Imaging of these patients consisted in fundus autofluorescence (FAF) as well as spectral-domain optical coherence tomography (Spectralis HRA+OCT™) and polarization-sensitive optical coherence tomography (PS-OCT). The area of atrophy in the follow up was measured manually in FAF with the region overlay device and in SD-OCT B-scans using a novel designed software enabling to grade complete SD-OCT volume scans and projecting the graded area to a en face image delineating exactly the measured area. Automated segmentation of GA was possible using a software algorithm designed to assess the area of atrophy in PS-OCT.

 

Results:

 

The areas of atrophy manually measured by FAF over the complete follow- up were very similar and correlated significantly with the area manually delineated in SD-OCT B-scans and the automatic segmentation of the area of atrophy in PS-OCT. Furthermore the measured enlargement of the area of atrophy was continuous in all retinal imaging devices.

 

Conclusions:

 

The results of this study confirm the hypothesis of monitoring patients with GA by SD-OCT and PS-OCT in determining the atrophy lesion size in a follow up study and in a monotonous manner, as FAF is capable of performing, and furthermore expected by the pathophysiology of the disease.

 

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