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Klin Monbl Augenheilkd 2023; 240(05): 650-661
DOI: 10.1055/a-2063-8957
Übersicht/Review

The Blood-ocular Barriers and their Dysfunction: Anatomy, Physiology, Pathology

Article in several languages: deutsch | English
Barbara M. Braunger
1   Institut für Anatomie und Zellbiologie, Julius-Maximilians-Universität Würzburg, Medizinische Fakultät, Deutschland
,
Andreas Gießl
2   Augenklinik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Medizinische Fakultät, Erlangen, Deutschland
,
Ursula Schlötzer-Schrehardt
2   Augenklinik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Medizinische Fakultät, Erlangen, Deutschland
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Abstract

Complex barriers comprise the blood-aqueous (BAB) and the blood-retinal barrier (BRB), and separate anterior and posterior eye chambers, vitreous body, and sensory retina from the circulation. They prevent pathogens and toxins from entering the eye, control movement of fluid, proteins, and metabolites, and contribute to the maintenance of the ocular immune status. Morphological correlates of blood-ocular barriers are tight junctions between neighboring endothelial and epithelial cells, which function as gatekeepers of the paracellular transport of molecules, thereby limiting their uncontrolled access to ocular chambers and tissues. The BAB is composed of tight junctions between endothelial cells of the iris vasculature, endothelial cells of Schlemmʼs canal inner wall, and cells of the nonpigmented ciliary epithelium. The BRB consists of tight junctions between endothelial cells of the retinal vessels (inner BRB) and epithelial cells of the retinal pigment epithelium (outer BRB). These junctional complexes respond rapidly to pathophysiological changes, thus enabling vascular leakage of blood-derived molecules and inflammatory cells into ocular tissues and chambers. Blood-ocular barrier function, which can be clinically measured by laser flare photometry or fluorophotometry, is compromised in traumatic, inflammatory, or infectious processes, but also frequently contributes to the pathophysiology of chronic diseases of the anterior eye segment and the retina, as exemplified by diabetic retinopathy and age-related macular degeneration.

Key words

blood-ocular barriers - blood-aqueous barrier - blood-retinal barrier - tight junctions - diabetic retinopathy - age-related macular degeneration


Publication History

Received: 05 January 2023

Accepted: 21 March 2023

Article published online:
19 May 2023

© 2023. Thieme. All rights reserved.

Georg Thieme Verlag KG
Rüdigerstraße 14, 70469 Stuttgart, Germany

 

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