Oguchi disease

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Oguchi disease
Classification and external resources
ICD-9	368.61
OMIM	258100

Oguchi disease, also called congenital stationary night blindness, Oguchi type 1 or Oguchi disease 1, is an autosomal recessive form of congenital stationary night blindness associated with fundus discoloration and abnormally slow dark adaptation.

Clinical features

Oguchi disease present with nonprogressive night blindness since young childhood or birth with normal day vision, but they frequently claim improvement of light sensitivities when they remain for some time in a darkened environment.

On examination patients have normal visual fields but the fundi have a diffuse or patchy, silver-gray or golden-yellow metallic sheen and the retinal vessels stand out in relief against the background.

A prolonged dark adaptation of three hours or more, leads to disappearance of this unusual discoloration and the appearance of a normal reddish appearance. This is known as the Mizuo-Nakamura phenomena and and is thought to be caused by the overstimulation of rod cells.

Differential diagnosis

Other conditions with similar appearing fundi include

• Cone dystrophy
• X-linked retinitis pigmentosa
• Juvenile macular dystrophy

These conditions do not show the Mizuo-Nakamura phenomenon.

Electroretinographic studies

Oguchi's disease is unique in its electroretinographic responses in the light- and dark-adapted conditions. The A- and b-waves on single flash electroretinograms (ERG) are decreased or absent under lighted conditions but increase after prolonged dark adaptation. There are nearly undetectable rod b waves in the scotopic 0.01 ERG and nearly negative scotopic 3.0 ERGs.

Dark-adaptation studies have shown that highly elevated rod thresholds decrease several hours later and eventually result in a recovery to the normal or nearly normal level.

The S, M and L cone systems are normal.

Cause and Genetics

Oguchi disease has an autosomal recessive pattern of inheritance.

Several mutations have been implicated as a cause of Oguchi disease. These include mutations in the arrestin gene or the rhodopsin kinase gene.

Type	OMIM	Gene
Type 1	258100	SAG
Type 2	613411	GRK1

The condition is more frequent in individuals of Japanese ethnicity.

History

It was described by Chuta Oguchi (1875-1945), a Japanese ophthalmologist, in 1907. The characteristic fundal appearances were described by Mizuo in 1913.

External links

• Template:RareDiseases

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