Table 1 Clinical signs of retinitis pigmentosa and cone-rod dystrophy

Visual function

Impaired night vision (nyctalopia), myopia (frequently), progressive loss of visual acuity

Visual field

Loss of peripheral vision in early stages, progressive loss of central vision in later stages, ring scotoma, tunnel vision

Eye fundus

Bone spicule deposits in peripheral retina, attenuation of retinal vessels, waxy pallor of the optic disc

Eye movement

Nistagmus

Electroretinogram

Diminution or abolishment of the a-waves and b-waves