Retinal dystrophies - External and Internal Eye
More than 120 genes have been shown to have mutations contributing to different phenotypic retinal dystrophies. These mutations can be autosomal recessive, autosomal dominant, X-linked, or sporadic. Furthermore, same gene mutations have been shown to have variable phenotypes.
Some diseases affect the rods only, others affect cones only, and some affect both rods and cones. Rod-dominated diseases include RP and congenital stationary night blindness (CSNB). Cone-dominated diseases include diseases such as Stargardt disease and achromatopsia. Cone-dominated diseases tend to be much more severe as the cones affect higher visual acuity and color perception. Combined rod-cone diseases include Leber congenital amaurosis (LCA), choroideremia, and gyrate atrophy.
In CSNB, the autosomal recessive and X-linked forms present with nystagmus, strabismus, and poor vision during infancy that remains nonprogressive. The autosomal dominant form of CSNB typically presents with normal visual acuity until the second decade, when patients start to exhibit progressive night blindness.
Two types of achromatopsia are autosomal recessive forms that exhibit nystagmus, poor vision, and photophobia in bright light during infancy. The third form of achromatopsia is X-linked recessive and less severe than the autosomal recessive forms. It also presents with nystagmus and photophobia during infancy.
LCA manifests in the first year of life and has a poor prognosis. Features include poor central vision and nystagmus.
Choroideremia starts in the first decade of life with complaints of night blindness and gradually progresses until the fifth decade, when there is a rapid decline in vision, resulting in a small central island of vision.
Note: To view images, see individual summaries, ie, retinitis pigmentosa and Stargardt disease.
H35.50 – Unspecified hereditary retinal dystrophy
314407005 – Retinal dystrophy
Differential Diagnosis & Pitfalls