Purpose: To assess the agreement between blue autofluorescence (BAF) and green autofluorescence (GAF) fundus imaging in measuring the macular hyperautofluorescent (hyperAF) ring in patients with inherited retinal diseases (IRDs).
Design: A prospective, within-subject agreement study.
Subjects: A total of 124 patients with IRD (67% with retinitis pigmentosa, 33% with cone-rod/macular dystrophies) from Moorfields Eye Hospital were included. Mean age was 36.5 years; 60% were male. Most (99%) had a genetically confirmed diagnosis.
Methods: Participants underwent BAF (Heidelberg) and GAF (Optos) imaging during the same visit. Hyperautofluorescent ring area and horizontal and vertical diameters were independently measured by 2 ophthalmologists. Agreement between imaging modalities was assessed using intraclass correlation coefficients, Pearson correlation, paired t tests, linear and mixed-effects regression, Bland-Altman plots, and 1-sided z-tests for equivalence within a ±10% margin.
Main outcome measures: Comparison of hyperAF ring area and diameters between BAF and GAF.
Results: Intergrader agreement was excellent (intraclass correlation coefficient: 0.93-0.98). Blue autofluorescence measured slightly larger ring areas than GAF (mean difference: 0.7 mm2, P = 0.006), while horizontal and vertical diameters were nearly equivalent (mean differences: 0.03 μm and 0.08 μm, P = 0.96 and P = 0.04, respectively). Discrepancies >10% were observed in 17% of cases in horizontal diameter, 27% of cases in vertical, and 42% of cases in area. Correlations were high (r = 0.98) for all metrics. Mixed-effects models including both eyes (n = 217) estimated that the area measured in GAF is 4.1% smaller than in BAF, the horizontal is approximately 0.5% smaller, and the vertical is around 2.2% smaller, with evidence of agreement within a ±6% margin at a 5% significance level.
Conclusions: High correlation and consistent regression slopes were seen between BAF and GAF macular hyperAF ring. These results suggest that while the 2 modalities yield broadly comparable measurements, with BAF yielding larger values, these modalities should ideally not be used interchangeably.
Financial disclosures: Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.
Keywords: Autofluorescence; Dystrophy; Genetics; Imaging; Retina.
© 2025 by the American Academy of Ophthalmology.