Blood-retinal barrier

The blood-retinal barrier, or the BRB, is part of the blood-ocular barrier that consists of cells that are joined tightly together in order to prevent certain substances from entering the tissue of the retina. [Biologyonline.org. [http://www.biology-online.org/dictionary/Blood-retinal_barrier Blood-retinal barrier] . Retrieved on July 19, 2007.] It consists of non-fenestrated capillaries of the retinal circulation and tight-junctions between retinal epithelial cells preventing passage of large molecules from choriocapillaris into the retina. The blood retinal barrier has two components: the retinal vascular endothelium and the retinal pigment epithelium. [Vinores SA. 1995. Assessment of blood-retinal barrier integrity. "Histology and Histopathology", Volume 10, Issue 1, Pages 141-154. PMID 7756735. Retrieved on July 19, 2007.] Retinal blood vessels that are similar to cerebral blood vessels maintain the inner blood-ocular barrier. This physiological barrier comprises a single layer of non-fenestrated endothelial cells, which have tight junctions. These junctions are impervious to tracer, so many substances can impact the metabolism of the eyeball. The retinal pigment epithelium maintains the outer blood-retinal barrier. [Pardianto G et al. 2005. Blood-retinal-barrier. "Mimbar Ilmiah Oftalmologi Indonesia". Volume 2, Pages 68-69.]

Diabetic retinopathy, eye damage that frequently occurs as a result of diabetes, is related to the breakdown of the blood-retinal barrier. [Azza B. El-Remessy, Mohamed Al-Shabrawey, Yousuf Khalifa, Nai-Tse Tsai, Ruth B. Caldwell and Gregory I. Liou. 2006. [http://ajp.amjpathol.org/cgi/content/abstract/168/1/235 Neuroprotective and Blood-Retinal Barrier-Preserving Effects of Cannabidiol in Experimental Diabetes.] "American Journal of Pathology", Volume 168, Pages 235-244. Retrieved on July 19, 2007.] The barrier becomes more leaky in patients with diabetic retinopathy. [Lobo CL, Bernardes RC, and Cunha-Vaz JG.2000. [http://archopht.ama-assn.org/cgi/content/abstract/118/10/1364 Alterations of the Blood-Retinal Barrier and Retinal Thickness in Preclinical Retinopathy in Subjects With Type 2 Diabetes.] "Archives in Ophthalmology", Volume 118, Pages 1364-1369. Retrieved on July 19, 2007.]

Animal models have shown that the blood-retinal barrier becomes more permeable to substances in hypertensive animals (those with high blood pressure). [S Lightman, E Rechthand, C Latker, A Palestine and S Rapoport. [http://hyper.ahajournals.org/cgi/content/abstract/10/4/390 Assessment of the permeability of the blood-retinal barrier in hypertensive rats.] "Hypertension", Volume 10, Pages 390-395. Retrieved on July 19, 2007.]

ee also

*Blood-brain barrier

References