Retinitis pigmentosa is a generic name for an inherited retinal degeneration, characterized clinically by typical appearances on ophthalmoscopy, with peripheral pigmentation of "bone-spicule" type, arteriolar attenuation, and eventually unmasking of choroidal vessels and optic atrophy. This process may be asymptomatic in its early stages, but may later be a cause of nyctalopia (night blindness), and produce a mid-peripheral ring scotoma on visual field testing.
A variety of genetic causes of isolated retinitis pigmentosa have been partially characterized:
- autosomal recessive: linked to chromosome 1q
- X-linked: Xp11, Xp21
- autosomal dominant: 3q, 6p, 8
In most cases, patients with retinitis pigmentosa have no associated systemic or extraocular abnormalities, but there are a number of multisystem disorders in which it occurs:
- Abetalipoproteinemia (Bassen-Kornzweig syndrome)
- Kearns-Sayre syndrome, mitochondrial disorders in general
- Lawrence-Moon-Bardet-Biedl syndrome
- Refsum’s disease
- Usher’s syndrome.