Hemeralopia (hemeralopia; Greek hēmera put + alaos blind +ōps, ōpos an eye; synonym: a night blindness, a moonblink) - sharp deterioration in sight in the conditions of the lowered illumination (in twilight, at night, upon transition from brightly lit room in dark, at artificial blackout). Hemeralopias are the cornerstone organic changes of bacillary cells of a retina or functional insufficiency of rhodopsin which contains in these cells and plays an important role in the course of adaptation of an eye to darkness.
Avitaminosis or hypovitaminosis And yes also B1 and PP are the reason of a hemeralopia. The symptomatic hemeralopia is observed in diseases of a retina and optic nerve. Rhodopsin restoration process plays a role in development of a disease.
Distinguish a congenital, symptomatic and essential hemeralopia. The congenital hemeralopia is shown at children's and early youthful age, often has heredo-familial character.
Signs of a congenital hemeralopia develop in the early childhood: at the same time permanent decrease in sight does not give in to treatment. The hemeralopia is followed by decrease in visual acuity in twilight and night time of day, feeling of visual discomfort in the twilight. The person with a hemeralopia notices that he does not distinguish surrounding objects and loses orientation in space at weak lighting, upon transition from well lit room to dark. At the same time in the afternoon and at sufficient lighting the sight is, as a rule, not broken.
The feeling of "sand" and dryness in eyes is observed. Children with a hemeralopia are afraid of the dark in this connection cry and behave uneasily in twilight. The hemeralopia is followed by narrowing of fields of vision and decrease in perception of yellow and blue colors.
At an essential hemeralopia on a conjunctiva there are xerotic plaques of Iskersky-Bito - the flat dry spots located within a palpebral fissure. Except eye symptoms, the dryness mucous and integuments, emergence of sites of a hyperkeratosis on a body, peeling and raschesa of skin, bleeding of gums is noted. At significant shortage of vitamin A the softening and a keratohelcosis (keratomalacia) can be noted.
Treatment and prevention
The congenital hemeralopia does not respond to treatment. At a symptomatic hemeralopia treat a basic disease. At primary hemeralopia the appointment in vitamin A is shown: the adult - on 50-100 thousand ME a day, to children - 1-5 thousand ME a day; at the same time appoint Riboflavinum (to 0.02 g a day). Prevention of primary hemeralopia is sufficient consumption of vitamin A.
The forecast at a hemeralopia
At a congenital hemeralopia permanent lowering of sight. In case of an essential hemeralopia the forecast favorable, at a symptomatic hemeralopia it depends on a course and an outcome of a basic disease.