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Comparison of Clarus, Optos, and Heidelberg Systems for Geographic Atrophy Area Measurements
Jacob Bogost1,2, Thomas Saunders2, Jennifer Heathcote2
1A-EYE Research Unit, Dept of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, Wisconsin.
Ophthalmology Science
|June 15, 2026
Summary
Fundus autofluorescence imaging platforms show reproducible geographic atrophy measurements but differ systematically. Consistent use of the same device is recommended for clinical trials evaluating geographic atrophy.
Area of Science:
- Ophthalmology
- Medical Imaging
- Retinal Diseases
Background:
- Geographic atrophy (GA) is a leading cause of vision loss in age-related macular degeneration.
- Accurate measurement of GA area is crucial for monitoring disease progression and evaluating treatment efficacy.
- Standardization of GA area measurements across different fundus autofluorescence (FAF) imaging devices is needed.
Purpose of the Study:
- To compare geographic atrophy (GA) area measurements across three modern FAF imaging platforms: Heidelberg Spectralis, Optos California, and Zeiss Clarus 700.
- To assess the agreement and systematic differences in GA area measurements obtained from these different FAF devices.
Main Methods:
- A prospective, cross-sectional study involving 61 eyes from 39 participants aged 50 years or older with GA.
- Sequential imaging of participants' eyes on the same day using Optos California, Zeiss Clarus 700, and Heidelberg Spectralis FAF devices.
- Manual planimetry segmentation for all modalities, with Heidelberg images also analyzed using semiautomated RegionFinder software as the reference standard.
Main Results:
- High agreement (intraclass correlation coefficients: 0.96-0.99) was observed in GA area measurements across all imaging systems when compared to the reference standard.
- Systematic differences in GA area measurements were noted between platforms and excitation wavelengths.
- Specifically, the Zeiss Clarus 700 (green channel) and Heidelberg Spectralis (manual) measured larger GA areas, while the Optos California measured smaller areas compared to the reference.
Conclusions:
- Geographic atrophy area measurements are reproducible within individual FAF imaging systems.
- However, systematic differences exist between measurement results from different FAF platforms and wavelengths.
- For clinical trials, consistent use of the same FAF imaging device is recommended for reliable GA area assessment.
