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 disk (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 defined as visual acuity less than 6/60 (20/200 in US notation; 0.1 in decimal notation) but at least 3/60 (20/400 in US notation; 0.05 in decimal notation).

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.