Abstract
Purpose :
The dynamics of photoreceptor activity in changing light conditions are crucial for vision and ocular health. Photoreceptor bleaching with intense light exposure alters retinal transparency and decreases visual sensitivity. In this study, we aim to understand the uniformity of clinical autofluorescence cameras and to observe photobleaching with these instruments.
Methods :
We evaluated different fundus autofluorescence (FAF) cameras for image granularity around the perifovea. Spectralis, Optos, and Clarus cameras were used to assessing the impact of mydriasis. Images were aligned using i2k Retina software, and FAF image consistency was determined by measuring grayscale pixel intensity around the perifovea in ImageJ. We also developed an apparatus to photobleach the retina, quantifying FAF image uniformity between bleached and unbleached retina.
Results :
In this study, Optos widefield FAF showed the lowest variability in non-dilated and dilated eyes. Spectralis was less reliable in capturing fundus photographs of the retina in non-dilated subjects. Optos FAF in non-dilated eyes produced grayscale image Coefficient of Variance of 6.85% vs. 4.60% in dilated eyes (Fig. 1b), compared to other cameras with variances of 17-24%. Optos FAF images exhibited greatest contrast in the photobleached retina (Fig. 2). Variance analysis decreased when short paths were evaluated by grayscale analysis.
Conclusions :
Imaging with the Optos camera produced the most uniform FAF images under mydriatic and non-mydriatic conditions. Contrast of blood vessels affected FAF image variability, necessitating short-path analysis to avoid artificial influences from blood vessel shadow. Clarus and Optos produced images with low contrast, minimizing the effect of blood vessels on FAF image variability. This preliminary experience encourages using the Optos imaging protocol for non-dilated eyes to study retinal photobleaching further.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.