Blood–ocular barrier explained

The blood–ocular barrier is a barrier created by endothelium of capillaries of the retina and iris, ciliary epithelium and retinal pigment epithelium.^[1] It is a physical barrier between the local blood vessels and most parts of the eye itself, and stops many substances including drugs from traveling across it.^[2] Inflammation can break down this barrier allowing drugs and large molecules to penetrate into the eye.^[3] As the inflammation subsides, this barrier usually returns.

It consists of the following components:

• Blood–aqueous barrier: the ciliary epithelium and capillaries of the iris.^[2] Blood-aqueous barrier is formed by nonpigmented ciliary epithelial cells of the ciliary body and endothelial cells of blood vessels in the iris.
• Blood–retinal barrier: non-fenestrated capillaries of the retinal circulation and tight-junctions between retinal epithelial cells preventing passage of large molecules from choriocapillaries into the retina. Formed by endothelium of retinal vessels and epithelium of retinal pigment. ^{[4] [5]}

Notes and References

1. Book: Small animal ophthalmology: a problem-oriented approach. Robert L.. Peiffer. Simon M.. Petersen-Jones. 46. Elsevier Health Sciences. 2001. 978-0-7020-2570-9.
2. Book: Antiseptic prophylaxis and therapy in ocular infections: principles, clinical practice, and infection control. Axel . Kramer . Wolfgang . Behrens-Baumann. 72. Karger Publishers. 2002. 978-3-8055-7316-0.
3. Book: Antimicrobial therapy in veterinary medicine. Steeve . Giguère . John F. . Prescott . J. . Desmond Baggot. 366. Wiley-Blackwell. 2006. 978-0-8138-0656-3.
4. Book: Macular Edema: A Practical Approach . G. . Coscas . J. . Cunha-Vaz . A. . Loewenstein . G. . Soubrane. 59. Karger Publishers. 2010. 978-3-8055-9434-9.
5. Book: Slatter's fundamentals of veterinary ophthalmology . David J. . Maggs . Paul E. . Miller . Ron . Ofri . Douglas H. . Slatter. 455. Elsevier Health Sciences . 2008. 978-0-7216-0561-6.