The Essential Role of the Choriocapillaris in Vision: Novel Insights from Imaging and Molecular Biology

Abstract

The choriocapillaris, a dense capillary network located at the posterior pole of the eye, is essential for supporting normal vision, supplying nutrients, and removing waste products from photoreceptor cells and the retinal pigment epithelium. The anatomical location, heterogeneity, and homeostatic interactions with surrounding cell types make the choroid complex to study both in vivo and in vitro. Recent advances in single-cell RNA sequencing, in vivo imaging, and in vitro cell modeling are vastly improving our knowledge of the choroid and its role in normal health and in age-related macular degeneration (AMD). Histologically, loss of endothelial cells (ECs) of the choriocapillaris occurs early in AMD concomitant with elevated formation of the membrane attack complex of complement. Advanced imaging has allowed us to visualize early choroidal blood flow changes in AMD in living patients, supporting histological findings of loss of choroidal ECs. Single-cell RNA sequencing is being used to characterize choroidal cell types transcriptionally and discover their altered patterns of gene expression in aging and disease. Advances in induced pluripotent stem cell protocols and 3D cultures will allow us to closely mimic the in vivo microenvironment of the choroid in vitro to better understand the mechanism leading to choriocapillaris loss in AMD.

Comparison of the macular vascular densities between molecularly confirmed MODY patients with GCK variants and age-matched healthy controls

“…They discussed OCTA may not be in the expected position for ensuring an early diagnosis of DRP, and nowadays it cannot replace the clinical funduscopic examinations due to their statistically signi cant, but clinically insigni cant changes [20]. CC, which is a dense vascular network is essential for nutrition and oxygen supply of the outer retinal cells such as photoreceptors and retinal pigment epithelium to maintain normal vision [32]. Previous studies investigated the status of choroid in diabetes and DRP, and there is no widely accepted consensus regarding thickness of choroid.…”

Choroidal Mast Cells and Pathophysiology of Age-Related Macular Degeneration

“…In the context of AMD, several researchers have recently proposed that the degeneration or dysfunction of the choriocapillaris could precede, contribute to, or even initiate the pathophysiological process of AMD. As AMD primarily affects the macular region of the retina, the health of the underlying choriocapillaris is critical for maintaining the structural and functional integrity of the macula [ 17 , 18 , 19 ].…”