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Structure-Function Relationships in Geographic Atrophy Based on Mesopic Microperimetry, Fundus Autofluorescence, and
Souvick Mukherjee1, Thilaka Arunachalam1, Cameron Duic1
1National Eye Institute, National Institutes of Health, Bethesda, MD, USA.
Translational Vision Science & Technology
|February 5, 2025
Summary
Choroidal hypertransmission on OCT shows higher spatial agreement with vision loss in geographic atrophy (GA) than FAF-defined GA. This suggests its potential as an outcome measure in GA clinical trials.
Area of Science:
- Ophthalmology
- Medical Imaging
- Retinal Diseases
Background:
- Geographic atrophy (GA) is a leading cause of irreversible vision loss.
- Understanding the relationship between structural changes and visual function in GA is crucial for developing effective treatments.
- Current imaging modalities have limitations in fully capturing the extent of retinal damage.
Purpose of the Study:
- To analyze the spatial agreement between absolute scotomas (areas of no vision) and macular structural features in GA.
- To compare the concordance of scotomas with choroidal hypertransmission (a feature of complete retinal pigment epithelium and outer retinal atrophy - cRORA) versus fundus autofluorescence (FAF)-defined GA.
- To evaluate the utility of optical coherence tomography (OCT) and FAF in assessing visual function deficits in GA.
Main Methods:
- Longitudinal data from a phase II GA trial were analyzed using mesopic microperimetry and multimodal imaging.
- OCT line scans were assessed for choroidal hypertransmission, and FAF images for GA.
- The Dice similarity coefficient (DSC) was used to quantify spatial concordance between scotomas and structural atrophy features.
Main Results:
- The study included 24 participants with a mean follow-up of 26.8 months.
- A moderately high spatial concordance was found between absolute scotomas and GA structural features.
- Concordance was significantly higher for choroidal hypertransmission (mean DSC 0.70) compared to FAF-defined GA (mean DSC 0.67).
- Mean OCT choroidal reflectivity correlated strongly with scotoma presence and severity.
Conclusions:
- Choroidal hypertransmission, a key cRORA feature, demonstrates a slightly higher spatial agreement with vision loss than FAF-defined GA in patients with geographic atrophy.
- OCT imaging provides more comprehensive information regarding visual function compared to FAF alone.
- Despite discordance, microperimetry remains essential alongside imaging for a complete assessment in GA trials.
