Blood-eye barrier

from Wikipedia, the free encyclopedia

The blood-eye barrier is a physiological barrier in the eye that separates its blood-supplying uveal area from the retina and the anterior chamber and vitreous space. The necessity of this limit lies on the one hand in a protective function, on the other hand in the different biochemical composition of aqueous humor and vitreous body fluid with their refractive functions on the one hand and of blood plasma on the other. In addition to the penetration of pollutants and pathogens that cause disease, clouding could occur that would significantly restrict a clear and sharp image of the environment on the retina. A metrology method for quantification of the blood-retinal barrier is the fluorophotometry .

The blood-eye barrier is divided into two areas, which are located below or adjacent to the uvea.

Blood-aqueous humor barrier

The blood-aqueous humor barrier is located in the endothelial linings of the iris vessels and in the non-pigmented areas of the ciliary epithelium . It separates the anterior chamber from the vascular areas and prevents the entry of plasma proteins into the aqueous humor and thus its opacity. The electron microscopic detection of their localization can take place via horseradish peroxidase . The blood-aqueous humor barrier has a physiological defect that is located between the orris root and the freely permeable, fenestrated ciliary vessels. Pathological changes in the blood-aqueous humor barrier can lead to clouding and sticking due to the penetration of proteins and blood plasma.

Blood-retinal barrier

In all mammals, the blood supply to the retina is ensured by two different blood vessel systems. The retinal blood vessels fed by the central artery supply the inner retinal layers (including the inner granular layer) and show a non-fenestrated endothelium. The outer retinal layers (including the outer granular layer), on the other hand, which also contains the sensory cells of the retina, the rods or cones of which are in close contact with the pigment epithelium , are nourished by diffusion from blood vessels in the choroid .

A distinction is made between an internal and an external blood-retinal barrier. While the former is created by the close connections between the retinal endothelial cells, the latter is formed by closely connected epithelial cells of the retinal pigment epithelium and represents a barrier to the fenestrated capillaries of the choroid. The blood-retinal barrier prevents pathogens or toxins from penetrating, for example Blood circulation in the intercellular spaces of the retinal layers. Since this also relates to the permeability to the vitreous, the blood-retina barrier is also to be regarded as the blood-vitreous barrier .

Disturbances or pathological changes in the blood-retinal barrier can lead to macular edema , retinal hemorrhage or other retinal diseases ( retinopathies ). In the area of ​​the papilla there is a physiological gap in the supply of the tissue there.

See also

Individual evidence

  1. ^ Albert J. Augustin: Ophthalmology. Springer-Verlag, 2013, p. 824/986. ISBN 978-3-662-05922-7
  2. ↑ a b G. OH Naumann: Pathology of the eye . Springer-Verlag, 2013, pp. 409 ff. ISBN 978-3-642-96500-5
  3. ↑ a b Matthias Sachsenweger, Volker Klauß, Joachim Nasemann: Dual series ophthalmology . Georg Thieme Verlag, 2002, pp. 174 ff. ISBN 978-3-13-153012-7
  4. ^ A b Carl Erb, Torsten Schlote: drug eye therapy. Georg Thieme Verlag, 2010. ISBN 978-3-13-160045-5
  5. ^ Thomas Kohnen: Refractive Surgery. Springer-Verlag, 2011, p. 23. ISBN 978-3-642-05406-8
  6. ^ Anselm Kampik, Franz Grehn: Augenärztliche Differentialdiagnostik , Georg Thieme Verlag, 2008, pp. 207 ff. ISBN 978-3-13-118622-5