Description

• An eye disease in which progressive damage to the retina occurs with gradual loss of peripheral vision that eventually leads to significant visual impairment; signs often seen in childhood, but severe vision problems do not develop until adulthood
• Characterized by poor night vision, constricted visual fields, bone spicule-like pigmentation of the fundus, and electroretinographic evidence of photoreceptor cell dysfunction
• System(s) affected: nervous
• Synonym(s): rod-cone dystrophy; retinal dystrophy

Epidemiology

Incidence

• Predominant age
  • X-linked retinitis pigmentosa (RP) has the earliest onset of the major hereditary types; many X-linked patients are legally blind by age 30 years.
  • Autosomal dominant RP has a later onset than autosomal recessive or X-linked–recessive RP.
  • Leber congenital amaurosis, which is a variant of RP, presents at birth.
  • Late-onset RP typically is asymptomatic and unrecognized until age 40 to 50 years.
• Predominant sex: male > female

Prevalence
Affects ~1/4,000 people in the United States

Pediatric Considerations
Leber congenital amaurosis characterized by reduced vision from birth and impaired electroretinogram (ERG) responses from both cones and rods.

Geriatric Considerations
Late-onset RP is asymptomatic and generally unrecognized until >40 years of age.

Etiology and Pathophysiology

• Mutations in the rhodopsin gene account for ~30% of cases of autosomal dominant RP.
• Another 4–6% of autosomal dominant RP is caused by a mutation in the gene for a photoreceptor protein peripherin/RDS.

Genetics

• Autosomal dominant: 20%
• Autosomal recessive: 37%
• X-linked recessive: 4.5%
• Sporadic: 38.5%

Risk Factors

Family history

General Prevention

• Genetic counseling
• No conclusive evidence demonstrates that the amount of light modifies the course of RP. A study in which one eye was covered with an opaque lens did not show any difference in disease progression compared with the fellow eye.
• Ultraviolet (UV)-absorbing sunglasses and brimmed hats are recommended when patients are at the beach or in the snow.

Commonly Associated Conditions

With systemic disorders

• Usher syndrome: RP and congenital sensorineural hearing impairment
• Laurence-Moon-Biedl syndrome (also called Bardet-Biedl syndrome): autosomal recessive disorder associated with retinal dystrophy, mental retardation, obesity, hypogonadism, and postaxial polydactyly
• Cockayne syndrome: autosomal recessive disorder in which children at the age of 1 to 2 years present with retinal dystrophy, sensorineural deafness, cerebellar dysfunction, dementia, and UV light photosensitivity