Retinitis pigmentosa (RP) is a genetic disorder of the eyes that causes loss of vision. Symptoms include trouble seeing at night and decreased peripheral vision (side vision).As peripheral vision worsens, people may experience "tunnel vision". Complete blindness is uncommon. Onset of symptoms is generally gradual and often in childhood.
Retinitis pigmentosa is generally inherited from a person's parents. Mutations in one of more than 50 genes are involved. The underlying mechanism involves the progressive loss of rod photoreceptor cells in the back of the eye. This is generally followed by loss of cone photoreceptor cells. Diagnosis is by an examination of the retina finding dark pigment deposits. Other supportive testing may include an electroretinogram, visual field testing, or genetic testing.
There is currently no cure for retinitis pigmentosa. Efforts to manage the problem may include the use of low vision aids, portable lighting, or a guide dog. Vitamin A palmitate supplements may be useful to slow worsening. A visual prosthesis may be an option in certain people with severe disease. It is estimated to affect 1 in 4,000 people.
The initial retinal degenerative symptoms of retinitis pigmentosa are characterized by decreased night vision (nyctalopia) and the loss of the mid-peripheral visual field. The rod photoreceptor cells, which are responsible for low-light vision and are orientated in the retinal periphery, are the retinal processes affected first during non-syndromic forms of this disease. Visual decline progresses relatively quickly to the far peripheral field, eventually extending into the central visual field as tunnel vision increases. Visual acuity and color vision can become compromised due to accompanying abnormalities in the cone photoreceptor cells, which are responsible for color vision, visual acuity, and sight in the central visual field. The progression of disease symptoms occurs in a symmetrical manner, with both the left and right eyes experiencing symptoms at a similar rate. A variety of indirect symptoms characterize retinitis pigmentosa along with the direct effects of the initial rod photoreceptor degeneration and later cone photoreceptor decline. Phenomena such as photophobia, which describes the event in which light is perceived as an intense glare, and photopsia, the presence of blinking, swirling or shimmering lights within the visual field, often manifest during the later stages of RP. Findings related to RP have often been characterized in the fundus of the eye as the "ophthalamic triad".
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Journal of optometry : open access