ELECTROPHYSIOLOGY OF THE ORGAN OF SIGHT

From Big Medical Encyclopedia

ELECTROPHYSIOLOGY OF THE ORGAN OF SIGHT — — the section of an electrophysiology studying the bioelectric phenomena in an organ of sight and also mechanisms of action on it electric current.

The first attempts of studying of bioelectric processes in an organ of sight connect with a name of Volta (A. Volta, 1792), the feeling of a weak luminescence which described emergence in an eye at a transmission through it electric current (such luminescence received the name «phosphene» and it is used in a wedge. to practice at a research of a functional condition of a retina of an eye and optic nerve). In 1849 E. Du Bois-Reymond proved existence of constant potential on a retina of an eye. In 1875 Mr. R. Caton for the first time established change of nature of bioelectric activity of a brain in response to irritation of an organ of sight by light. In the subsequent works of scientific many countries results of researches of sense bodys were generalized that served one of bases of creation of an electrophysiology (see) as independent section of physiology (see). Progress in development E. lake z. it is connected with development of the new equipment for registration of bioelectric potential, and further — microelectrode technics of their assignment (see Bioelectric potential, the Microelectrode method of a research). By means of intracellular assignment of potentials the component structure of the electroretinogram was established (see Elektroretinografiya), correlation between photochemical processes and action potential of a retina (see Sight), etc. is revealed. By this time carry also the beginning of development of methods clinical E. lake z. Subsequent development E. lake z. it is connected with basic physiological researches of receptive fields of visual system.

By means of synchronous registration of bioelectric activity sthuktur the visual analyzer at all levels of its organization (an electroencephalography of visual system) the mechanism of spatio-temporal characteristics of receptive fields and their dynamic properties was studied that was one of premises of creation of the scientific concept about transformation in visual departments of bark of a great brain of the images projected on a retina of an eye.

In a wedge. ophthalmology the condition of visual pathways and the centers studied in the beginning by means of background EEG (see Elektroentsefalografiya), and further — method of visual evoked potentials (registration of average potential of electric activity of a visual cerebral cortex at light stimulation of a retina). As an incentive at the same time apply diffusion light flash or other, more difficult visual irritants. Simultaneous record of the electroretinogram and visual evoked potentials allows to estimate time of passing of visual excitement from a retina to visual bark (so-called retinokortikalny time). This method is used at diagnosis of damages of an optic nerve and visual pathways, at assessment of a condition of sight at children, at identification of simulation of a blindness etc.

Clinical E. lake z. holds rather independent position in ophthalmology. Solve many diagnostic problems (e.g., carry out assessment of a condition of sight at opaque optical environments of an eye) with its help, predict an outcome of nek-ry hereditary diseases of a retina, etc. Apply as objective methods of a research of visual system — an elektroretinografiya (see), an elektrookulografiya (see), an electroencephalography (see), etc., and subjective, e.g. a research of electric phosphene at irritation of an eye electric current by means of what make functional assessment of a condition of inner layers of a retina (a threshold of electric sensitivity of an eye) in axial a bunch of an optic nerve (its lability). Methods E. lakes apply also at a research of a hemodynamics of a vascular path or cover of an eyeglobe (see Reooftalmografiya) and a functional condition of the oculomotor device (see the Electromyography, Elektrookulografiya). By means of an elektrookulografiya study the movements of an eye, nek-ry kinds of a nystagmus (see), vestibular frustration (see Vestibulometriya), etc. Methods E. lake z. use also in other fields of medicine — neurosurgery, neurology, pharmacology, etc. Further improvement of methods E. lake z. it is connected with studying of ways of assignment and registration of local capacities of visual system and use of computer facilities for processing of results of diagnostic search.

G. M. Laryukhina.

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