Assessing Retinal Sensitivity in Geographic Atrophy Using OCT-Guided Microperimetry: Insights from the OREO Study

Abstract

Purpose : To demonstrate differences in retinal sensitivity of different anatomical areas of patients with geographic atrophy (GA), using an optical coherence tomography (OCT) guided microperimetery (MP) assessment longitudinally of prespecified region of interest (ROI), in comparison to aged-matched intermediate AMD (iAMD) and controls.

Methods : All subjects underwent a screening OCT and Fundus Autofluorescence (FAF) exam using Heidelberg Spectralis® and microperimetry exam using MAIA® as part of the OREO Study (prospective observational study of disease progression of iAMD and GA). Areas of GA and transition zone (TZ) were identified using FAF and OCT imaging and annotated for subjects with GA (Fig 1). Custom MATLAB software was developed to register the annotated images from OCT to the IR image from MAIA. Eight MP points were added to TZ in a start shaped pattern and similar number and direction were added to the normal retina. Four points were added to the area of the GA (Fig. 1). A follow-up MP exam was performed on MAIA to test the ROIs. Patients with iAMD and controls underwent a 20-deg MP exam with 5 concentric rings, 2 degrees apart. Follow-up exams were performed on each subject each quarter. Stanford’s institutional review board (IRB) had approved the study.

Results : Seven (7) GA, 38 iAMD and 35 control eyes were included in this interim analysis. The overall mean retinal sensitivity was 24.1 dB, 22.9 dB, and 16.4 dB for controls, iAMD and GA, respectively. The mean retinal sensitivity by ring for iAMD was consistently lower than age-matched controls. Eyes with iAMD lost approximately 2 db in mean sensitivity in rings closer to fovea (R1-R3) compared to 1 dB in R4 and R5 over 36 weeks. Eyes with GA lost 3.3 dB in the GA area, 1.4 dB in the TZ and 0.4 dB in the normal retina over 12 weeks. Controls retained the mean sensitivity in all rings over 36 weeks (range: -0.1 to 0.2 dB).

Conclusions : MP of prespecified ROI in patients with GA is possible and shows changes in function that are apparent before any structural change is observed on FAF imaging. This methodology can reliably reduce the time of MP exam and increase the yield by selecting clinically significant regions.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.

 

A representative image of subject with geographic atrophy with MP spots in the GA lesion (red), transition zone (yellow) and healthy retina.

 

Mean Retinal Sensitivity by Rings at Baseline