<unk>  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 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<unk> '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.
Oguchi disease
Chandler's disease
Sequela
Dent's disease
Sever's disease
Freiberg disease
Bornholm disease
Van Buchem disease