PHOTOPSIA

From Big Medical Encyclopedia

FOTOPSYYa (Greek phos, photos light + opsis sight) — false subjective sensation of light in eyes in the form of sparks, flashes, the shining lines, rings, spots, fiery surfaces, zigzags, lightnings, gloss, etc., arising at inadequate stimulation neuro and receptor or the carrying-out and central departments of the visual analyzer.

T. is a kind of the visual phenomena combined under the general name «entoptiche-sky», i.e. caused by reaction of internal structures of an eye.

Main reasons F. serve patol. the processes developing in an eye, napr, a choroiditis (see), neuritis and other diseases of an optic nerve (see), tumors, amotio of a retina (see). T. can be early symptoms of these patol. processes. Besides, F. it can be caused also by disturbance of blood circulation in vessels of a retina (see the Choroid of an eye), and also other departments of the visual analyzer (see. Visual centers, ways). Example such F. «ciliary» scotoma, or eye migraine is — the bright flashes of light, zigzags, lines in some cases preceding the developed picture of migraine (see).

Are quite various F., caused by mechanical or electric irritation of any site of the visual analyzer (see) — phosphene. E.g., during the pressing the visual feeling of light owing to irritation of a retina arises a finger on an internal or outside corner of an eye. To relatives the feeling of flash of light by origin is at the sharp movement of eyes and accommodation, a cut is also explained by mechanical irritation of a retina the fluctuating vitreous. The technique of a research of safety of functions of a retina and optic nerve is based on definition of a threshold of electric sensitivity. Functional safety of a retina is estimated in size of the electric irritation causing phosphene.

Bibliography: The multivolume guide to eye diseases, under the editorship of V. N. Arkhangelsky, t. 1, book 2, page 118, M., 1962; Shmelyova V. V. Fenomen_ Moura, Vestn. oftalm., No. 5, page 80, 1975;

A d-1 e r F. N of Physiology of the eye, Clinical application, p. 179, St Louis, 1975; Bowen S. F. Retinal entoptic phenomena, Arch. Ophthal., v. 69, p. 551, 1963; Helmholtz H. Handbuch der physiologischen Optik, S. 175, Hamburg — Lpz., 1896; Morse P. H., Scheie H. G. a. A m i n 1 a r i A. Light flashes as a clue to retinal disease, Arch. Ophthal., v. 91, p. 179, 1974.

H. H. Pivovarov.

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