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. The rod system is damaged but cones are also involved to some degree and the electroretinogram amplitude is subnormal. The condition is usually bilaterally symmetrical. Many cases are caused by mutations in the rhodopsin gene (RHO). The inheritance can be autosomal dominant, autosomal recessive or X-linked. It is in most cases an inherited disease caused by abnormalities of many genes and characterized by night blindness (nyctalopia) and constricted visual fields. Also known as tapetoretinal degeneration or pigmentary retinopathy.Ī primary pigmentary dystrophy of the retina followed by migration of pigment. There is no specific treatment but nutritional supplements including omega-3-rich fish oils are believed to slow progress. Some recessive forms are caused by mutations in ABCA4 GENES. A small proportion of cases are due to a gene mutation that prevents retinaldehyde from being converted to the form used by retinal photoreceptors. The remainder are also believed to be caused by gene mutations. In 60 percent of cases it has a known genetic basis and more than 45 causal genes have been identified. Retinitis pigmentosa varies greatly in age of onset and severity. This condition is not inflammatory and the term is misnomer. Initially, this causes night blindness only but later there is progressive loss of an ever-enlarging area of the peripheral field of vision. Medical Dictionary for the Health Professions and Nursing © Farlex 2012 retinitis pigmentosa A slow degenerative disorder of the rods and cones of the RETINAS of both eyes with migration of pigment from the retinal pigment layer.
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