From Big Medical Encyclopedia

POLYOPIA (polyopia; grech, poly is a lot of + ops, op[os] of eyes) — disturbance sight , at Krom the single subject is perceived as several objects. The item meets seldom. Education in optical environments of an eye (a cornea, a crystalline lens) of the sites which are unequally refracting light rays therefore on a retina several images of one subject are projected is the cornerstone of it. Such conditions can arise at the limited unsharply expressed opacifications of a cornea, at emergence in a crystalline lens of the focal opacifications which are observed in initial stages of a cataract and also at cone-shaped protrusion of the central site of a cornea (keratoconus) or a crystalline lens (lenticonus).

Special case of P. is the monocular diplopia, napr, at an incomplete dislocation of a crystalline lens when one image on a retina arises at path of rays through the periphery of a crystalline lens, another — through the space deprived of a crystalline lens. The monocular diplopia sometimes arises at uneven consolidation of a kernel of a crystalline lens when it becomes as if bifocal. Sometimes P. is caused by a polycoria, i.e. existence of several pupillary openings in an iris as a result of anomaly of its development.

In addition to P. having an organic basis in some cases functional P. (e.g. is observed, at hysteria).

E. S. Avetisov.