Astigmatism - a combination in one eye of various kinds of an ametropia or various degrees of one kind of an ametropia.

Etiology, pathogenesis. Anomaly of a structure of eyes - radius of curvature of a cornea (seldom lens) in various meridians appears unequal. On two main mutually perpendicular meridians the strongest and most weak refractivity. As a result of this image of subjects on a retina always happen indistinct, deformed. Sometimes the astigmatism develops after operations, illnesses of a cornea, wounds of eyes. Distinguish its following kinds: a simple astigmatism - in one of the main meridians an emmetropia, in other - a myopia or a hypermetropia; a complex astigmatism - in both main meridians an ametropia of an identical kind, but a various degree; the admixed astigmatism - in one of the main meridians is observed a myopia, in other - a hypermetropia. Signs: dropping of vision, sometimes vision of subjects bent, fast fatigue of eyes at work, a headache.