A nonspecific term denoting degeneration of the retinal pigment epithelium and/or retinal photoreceptor cells of the macula lutea.

Inability to see well at night or in poor light.

Loss of peripheral vision with retention of central vision, resulting in a constricted circular tunnel-like field of vision.

A pale yellow discoloration of the optic disc (the area of the optic nerve head in the retina). The optic disc normally has a pinkish hue with a central yellowish depression.

Severe reduction of the ability to see. On the 6m visual acuity scale, severe reduction is defined as less than 6/60 but at least 3/60. On the 20ft visual acuity scale, severe reduction is defined as less than 20/200 but at least 20/400. On the decimal visual acuity scale, severe reduction is defined as less than 0.1 but at least 0.05.

Pigment migration into the retina in a bone-spicule configuration (resembling the nucleated cells within the lacuna of bone).

An abnormality of the combined rod-and-cone response on electroretinogram.

An inherited retinal disease subtype in which the rod photoreceptors appear to be more severely affected than the cone photoreceptors. Typical presentation is with nyctalopia (due to rod dysfunction) followed by loss of mid-peripheral field of vision, which gradually extends and leaves many patients with a small central island of vision due to the preservation of macular cones.