retinitis punctata albescens


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retinitis punctata albescens

A nonprogressive, degenerative familial disease in which innumerable minute white spots are scattered over the entire retina. There are no pigmentary changes. The disease usually starts early in life.
See also: retinitis

retinitis pigmentosa (RP) 

A primary pigmentary dystrophy of the retina followed by migration of pigment. It is in most cases an inherited disease caused by abnormalities of many genes and characterized by night blindness (nyctalopia) and constricted visual fields. The inheritance can be autosomal dominant, autosomal recessive or X-linked. Many cases are caused by mutations in the rhodopsin gene (RHO). The condition is usually bilaterally symmetrical. The rod system is damaged but cones are also involved to some degree and the electroretinogram amplitude is subnormal. The disease usually begins in adolescence with night blindness, followed by a ring scotoma in the periphery that spreads until only a small contracted central field remains and vision is greatly reduced or completely lost. Ophthalmoscopic examination reveals a yellowish atrophy of the optic nerve, severe arterial attenuation and conspicuous pigment proliferation, which begins in the equatorial region. The areas of pigment have dense centres and irregular processes shaped like bone corpuscles. There are several variants (atypical RP) of pigment distributions and patterns throughout the fundus (e.g. in mainly one quadrant) or as retinitis punctata albescens (scattered white dots most numerous at the equator). Associated systemic syndromes include Bassen-Kornzweig, Kearns-Sayre, Laurence-Moon-Bardet-Biedl, Refsum's and Usher's. Syn. primary pigmentary retinal dystrophy. See visual field field; leopard fundus; tritanopia; tunnel vision.
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