Choriocapillaris: Fundamentals and advancements
Introduction
The choroid is the most vascular structure of the eye and has the highest blood flow per unit weight compared to any other tissue in the body (Alm and Bill, 1973). While the choroid has always been of considerable scientific and clinical interest, the recent dramatic increase in the number of publications on choroid is attributable in part to recent advances in imaging technology. Within the choroid, the choriocapillaris plays a critical role in supplying oxygen and nutrition to the outer retinal cells. In this review article, we comprehensively discuss the anatomy, histology, and physiology of the choriocapillaris with a particular emphasis on multimodal imaging. This overview is followed by an in-depth discussion on future avenues for investigation and therapeutic interventions. We conclude our review with pertinent research inquiries for choriocapillaris investigators that may provide insight and advancement for the overall vision science community.
Section snippets
From choroid to choriocapillaris
The choroid is a layered vasculature that provides oxygen and nutrients to the outer retina. It is located between the sclera and the retina, sitting directly below Bruch's Membrane (BM). The majority of the choroid is characterized by its layered vasculature, with stromal tissue occupying only about 20% of its volume (Sohrab et al., 2012). The structure of the choroid is divided into three layers of blood vessels; these layers are classified based on the diameter of the blood vessels. The
Axial length change
Induced myopia leads to compensatory choroidal thickening whereas induced hyperopia is characterized by thinning of the choroid with posterior displacement of the retina in chicks (Wallman et al., 1995). The choroid may also have a role in axial length regulation directly or indirectly via its effects on the sclera. It remains unclear whether the choroidal thickness is involved in emmetropic targets in humans. The regulation of choroidal thickness occurs via widening of capillary fenestrations,
Future imaging approaches
There are many questions which need to be answered about the choriocapillaris. These questions include whether choroidal circuit organization is serial or parallel, whether lobules are effective and if there are shunts between them; whether CNV originate from choriocapillaris, how the choriocapillaris blood flow is regulated, how RPE and the choriocapillaris enable co-survival of each other, and what are the unique features and of the peripheral choroid. Here are described the possible future
Arrangement of the choriocapillaris: is it lobular?
The anatomy of the choriocapillaris anatomy is still debated but the former idea of a continuous monolayer has grown controversial. The main description of the architecture of the choriocapillaris originates from histological studies. (“On Inflammation of the Choroid Coat,” 1830) However, the understanding of the choriocapillaris architecture has been studied using postmortem methods such as casts, as well as in vivo imaging such as fluorescein angiography (Ashton, 1952). The focal void induced
Conclusion
Even though the choriocapillaris represents a relatively small portion of the choroid in terms of volume, it plays an enormous role in the pathogenesis, evolution, and general history of retinochoroidal diseases. Our growing understanding of this unique vasculature will likely impact our overall understanding of many ocular conditions. Advances in imaging have provided novel opportunities to further evaluate the choriocapillaris for effective diagnosis and management in clinical practice. Thus,
Author statement
Raphael Lejoyeux: Writing - Original Draft, Methodology, Jennifer Benillouche: Writing - Original Draft, Joshua Ong: Validation, Writing - Review & Editing, Marie-Hélène Errera: Writing - Original Draft, Ethan A. Rossi: Writing - Original Draft, Resources, Sumit R. Singh: Writing - Original Draft, Kunal K. Dansingani: Validation, Writing - Review & Editing, Susana da Silvada Silvation, Writing - Review & Editing, Debasish Sinha: Validation, Writing - Review & Editing, José-Alain Sahel:
Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
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2023, Progress in Retinal and Eye ResearchCitation Excerpt :The localized BM defects may lead to a local outpouching of the sclera, similar to the occurrence of scleral staphylomas in spatial association with congenital BM defects, as in the case of colobomas, or in association with acquired BM defects in non–highly myopic eyes, such as in the case of toxoplasmotic scarring (Jonas, JB and Panda-Jonas, 2016). The choriocapillaris is a dense, mono-layered capillary network, the basal membrane of which covers the posterior surface of BM (Jonas, JB et al., 2011; Lejoyeux et al., 2022; Schachat et al., 2017) (Fig. 3). The choriocapillaris is the inner layer of the choroid.
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RL 14% JB 8% JO 3% MHE 8% EAR 7% SSR 4% KKD 7% SDS 3% DS 3% JAS 5% KBF 5% SSR 7% GAL 12% JC 14%.