Abstract
Purpose :
Fundus autofluorescence (AF) imaging aids diagnosis and phenotyping of retinal disease. Appearances differ depending on various parameters including wavelengths used. We compared brightness of the central foveal region obtained with two widely used imaging platforms in patients with disease associated with variants in CNGB3 (the gene most frequently associated with achromatopsia in our cohort).
Methods :
The electronic database of a large inherited retinal disease service was retrospectively searched for patients with molecularly confirmed CNGB3-associated disease. Patients with both blue AF (488 nm Spectralis, Heidelberg Engineering, Germany) and green AF (532 nm, Optos plc, Dunfermline, UK) acquired on the same visit were included. In case of multiple visits where both modalities were used, the most recent visit with gradable images was included. The central foveal signal was graded qualitatively in each eye as hyperautofluorescent or hypoautofluorescent relative to the wider macular region. A specific aim was to identify eyes with discrepancy between the two modalities.
Results :
Fifty patients met the above criteria. Six were excluded due to poor quality or unclassifiable images. Mean (SD) age of the 44 remaining patients (24 females) was 32 (18) years (ranging from 8 to 73). Each patient had the same grading for right and left eyes with each modality. For blue AF (Spectralis) images, the central foveal signal was graded hypoautofluorescent in all cases; in green AF (Optos) images, the central fovea was hyperautofluorescent in 12 cases (4 females). Mean (SD) age of these 12 patients was 22.8 (12.6) years, whilst mean (SD) age of the other 32 patients was 36.1 (18.7) years. The patients showing discrepancy were significantly younger (p=0.028).
Conclusions :
In 27% of patients, a discrepancy was observed between the two modalities whereby the central fovea appeared hyperfluorescent in green AF images, but not in blue AF images. These patients were significantly younger on average. No patients had an interocular discrepancy. Short wavelengths (488 nm) are absorbed by macular luteal pigment, whilst longer wavelengths (including 532 nm) are absorbed by M and L cone opsins. The sign identified in this study might aid diagnosis and potentially yield insights into structural alterations in achromatopsia.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.