The vascular geometry of the choriocapillaris is associated with spatially heterogeneous molecular exchange with the outer retina

J Physiol. 2024 Mar 21. doi: 10.1113/JP285050. Online ahead of print.ABSTRACTVision relies on the continuous exchange of material between the photoreceptors, retinal pigment epithelium and choriocapillaris, a dense microvascular bed located underneath the outer retina. The anatomy and physiology of the choriocapillaris and their association with retinal homeostasis have proven difficult to characterize, mainly because of the unusual geometry of this vascular bed. By analysing tissue dissected from 81 human eyes, we show that the thickness of the choriocapillaris does not vary significantly over large portions of the macula or with age. Assessments of spatial variations in the anatomy of the choriocapillaris in three additional human eyes indicate that the location of arteriolar and venular vessels connected to the plane of the choriocapillaris is non-random, and that venular insertions cluster around arteriolar ones. Mathematical models built upon these anatomical analyses reveal that the choriocapillaris contains regions where the transport of passive elements is dominated by diffusion, and that these diffusion-limited regions represent areas of reduced exchange with the outer retina. The width of diffusion-limited regions is determined by arterial flow rate and the relative arrangement of arteriolar and venular insertions. These analyses demonstrate that the apparent complexity of the choriocapillaris conceals a fine balance between several anatomical and functional paramet...

Source: The Journal of Physiology - March 21, 2024 Category: Physiology Authors: Caitlin D Faust Christian A Klettner Marc Toso Gregory S Hageman Ian Eames Philip J Luthert Moussa A Zouache Source Type: research