Abstract
Purpose :
Blue-peak fundus autofluorescence (BAF) is a widely used imaging technique to assess the functional integrity of the retinal pigment epithelium (RPE) layer of retina. Measuring the rate of increase of the area with definitely decreased autofluorescence (DDAF) is used to determine the progression of atrophic conditions such as geographic atrophy (GA) or Stargardt disease (SD). This is often used as an endpoint in clinical trials for treatments of the above mentioned conditions. This requires precisely marking the border of the lesion, which can be difficult if it is near the edge of the image, or around vessels. Our purpose was to develop a luminance-based method to measure the changes of the size of the atrophy.
Methods :
If the area of DDAF increases in a BAF image, the luminance of the image decreases. We have developed a program to track luminance of the BAF images of the same patient taken at different times.
The luminance of the image is influenced by different exposure times, fixation or pupil dilation. Therefore, on the first BAF image, we mark an area for reference, further from the atrophic lesion, which will be later automatically identified by the algorithm.
The change in luminance of these areas correlates with changes resulting from the above reasons, these must be subtracted from the luminescence of the given recording. The program also automatically recognizes these areas. A progression curve can be established from the changes in corrected luminance values. In order for the recordings to be comparable, the same resolution is required and the recordings must be in uncompressed file format. We used a Heidelberg Spectralis OCT device to obtain the images, but the measuring program is independent of the device.
Results :
With this method, the change was bequantified in either minor or extensive geographic atrophy. The method needs fine-tuning, but it can help in both diagnostics and drug development research.
Conclusions :
WIth this method, the progression of the atrophic lesions of the retinal outer segment could be assessed with a different, independent method aside from measuring the growing rate of area of DDAF.
This abstract was presented at the 2024 ARVO Imaging in the Eye Conference, held in Seattle, WA, May 4, 2024.