Abstract
Purpose :
Age-related macular degeneration (ARMD) is associated with extensive, dynamic redistribution of melanin at all stages. It has been shown that the evolution of this redistribution parallels expansion of atrophy; hence its clincial characterization at the microscopic level is of interest. Transscleral fundus imaging (TFI) is a novel technique that enables visualization of the retinal pigment empthelium (RPE) in normal eyes. Here, we documented eyes with dry ARMD by TFI.
Methods :
The transcleral illumination system is a CE-marked add-on of a commercially available adaptive optics flood illumination camera (rtx1, ImagineEye, France), with the same light source (flood 870nm) and operator interface. The simultaneous acquisition of transpupillary and transcleral images ensures pixel-to-pixel correspondence. Twenty patients (age range, 63-79y) with intermediate or late dry ARMD were longitudinally examined. Single 4°x4° images were montaged over a 8°x8° central area. Images were compared to optical coherence tomography (OCT) and near infrared autofluorescence (NIRAF). Changes over time in the distribution of features were documented.
Results :
Overall, TFI increased the contrast of NIRAF-positive (melanin) clumps while decreasing the contrast of drusen and of atrophic areas. In patients with intermediary AMD, compared to transpupillary illumination, TFI enabled a more precise delineation of hyperreflective foci (HRFs) and of pigment redistribution at the summit of drusen (thickened retinal pigment epithelium, tRPE). TFI enabled a high precision in the documentation of the dynamics of HRFs (see figure). TFI showed also a better delineation of refractile drusen, which are highly reflective features at the level of the Bruch's membrane. We also identified in 4 eyes a peculiar features during regression of drusen under the form of highly reflective structures, some adjacent to refractile drusen.
Conclusions :
Combining transpupillary and transscleral adaptive optics flood imaging improves the identification of microscopic features in dry ARMD such as HRFs and tRPE hence enlarging the precision of clinical phenotyping. The contrast of melanocytic spots and of refractile drusen, in particular, was notably improved. Novel features were identified, possibly related to drusen regression, that deserve further investigations.
This abstract was presented at the 2024 ARVO Imaging in the Eye Conference, held in Seattle, WA, May 4, 2024.