GEMATO-OFTALMICHESKIY BARRIER

From Big Medical Encyclopedia

GEMATO-OFTALMICHESKIY BARRIER (Greek haima, haimat[os] blood + ophthalmos of eyes) — the complex of physiological mechanisms regulating a metabolism between blood and liquids of an eye and the composition of intraocular liquids performing barrier function concerning fabrics and transparent environments of an eye.

Liquid of an anterior chamber of an eye considerably differs on structure from blood plasma: protein, enzymes and antibodies in chamber moisture are absent or contain in insignificant quantity. Penetration into chamber moisture and into a vitreous of nonelectrolytes is made in very difficult conditions. It is established that the speed of penetration of this or that nonelectrolyte into an anterior chamber cannot be caused only physical. factors (size of a molecule). Also the difference of concentration of electrolytes in chamber moisture and in blood cannot be explained with simple filtering or dialysis. The difference in distribution of various electrolytes in a blood plasma and in liquid of an anterior chamber of an eye does not submit also to the law of a Donnan equilibrium (see. Membrane equilibrium ). This law does not explain why one of the substances entered into blood can be found in liquid of an anterior chamber, and others, very close to them on chemical and physical. to properties, in it are not found.

Gistol, researches of drugs of eyes with vital staining suggest that morfol, substrate G. - the lake. the endothelium of vessels is and that the endothelium of capillaries of an eye carries out exchange between blood and intraocular liquids. Functions of an endothelium in this process are not passive and only physical are not limited. - chemical patterns. The endothelium of capillaries has a number of active properties thanks to existence of the difficult and thin mechanisms and systems (e.g., hyaluronic to - that is hyaluronidase, etc.) which are under the influence of neurohumoral factors. Various substances get into a vitreous, especially into its back layers, more slowly, than into chamber moisture. It demonstrates that capillaries of a retina possess more expressed barrier function, than capillaries of a choroid. Noticeable influence on function G. - the lake. the trifacial, and also a sympathetic nervous system renders.

On a functional condition of G. - the lake. also such factors as an inflammation exert impact. Inflammatory process in covers of an eye leads to sharp weakening of G. - the lake., i.e. to increase in permeability of an endothelium of vessels of an eye. In the same way on G. - the lake. the cathode galvanization and especially ionizing radiation work. Local, and also general irradiation X-ray can lead to sharp increase in permeability of vessels of a front piece of an eyeglobe.

See also Barrier functions .


Bibliography: Nuritdinov V. A. Permeability of a blood-ocular barrier and hydrodynamics engineer of eyes, Vestn, oftalm., Jslfl 5, page 30, 1971; P about m and sh e of the Tax Code about in F. A., Stebayeval. T. and Proshina L. Ya. Some topical issues of studying of age features of a blood-ocular barrier, Works of the 2nd Mosk. medical in-that, century 2, page 209, 1969, bibliogr.; With and in about sh and nanosecond to and y D. D. and Belov Yu. A. Advantages of a method of an autoradiography in pilot studies of a blood-ocular barrier, in the same place, page 215, bibliogr.; Brubaker R. F. a. Riley F. G. The filtration coefficient of the blood-aqueous barrier, Invest. Ophthal., v. 11, p. 752, 1972; Bucci M.& G. Apparato fluorometrico per indagini sulla per-mabilit della barriera emato-oftalmica, Boll. Oculist., y. 47, p. 61, 1968.

M. Ya. Fradkin.

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