Abstract
Purpose :
Aging is associated with various degenerative changes in the retina, including some of the most destructive and widespread ocular pathologies, such as glaucoma or age-related macular degeneration. As neurodegeneration is by nature evolving, distinguishing it from normal aging of the tissue is crucial. 2D histology (eg sectioning of tissues) may miss spatial information, since the manifestation of aging can be focal. Furthermore, the combined investigation of the aging retina and choroid is interesting since these structures are interdependent. Here we chose to use immunohistochemistry and confocal imaging to search for anatomical changes in retinal and choroidal cells across human donor’s tissues.
Methods :
Five human donors with no registered ocular diseases were analyzed. Peripheral retina and choroid underwent immunohistochemistry allowing investigation of different cell types and the protein expression patterns. As choroid and RPE are highly pigmented tissues, an original depigmentation protocol was developed and performed before immunohistochemistry. Retinal and choroidal samples were then whole-mounted and imaged using a confocal microscope, allowing 3D reconstruction of the cells population and structures of interest.
Results :
Observing photoreceptors, we observed a clear degradation of the cellular anatomy and opsin localization with increasing age. Cones and rods presented nuclei displacement towards the RPE and opsin mislocalization toward the IPL, a pattern which was clearly age-dependant. The oldest subjects also presented a high density of Iba1 positive migratory cells (phagocytes).
Ghost capillaries segments (acellular and/or obstructed) were conspicuous in the extreme periphery of the retinal vascular network, shrinking its maximal extension.
RPE cells increased in size, and more RPE cells detached from the Bruchs membrane during tissue preparation.
With age, the choriocapillaris density dramatically decreases, cell repartition changes (especially smooth muscle positive cells) and the whole tissue thinns.
Conclusions :
We are initiating here a systematic study of the manifestations of normal aging of retinal and choroidal tissues using immunohistochemistry. Microglial infiltration in the outer retina, ghosts capillaries, enlargement of RPE cells and modification of the photoreceptor intracellular arrangement were the most striking features.
This is a 2021 ARVO Annual Meeting abstract.