X-linked congenital stationary night blindness (CSNB) is characterized by non-progressive retinal findings of reduced visual acuity ranging from 20/30 to 20/200; defective dark adaptation; refractive error, most typically myopia ranging from low (-0.25 diopters [D] to -4.75 D) to high (=-10.00 D) but occasionally hyperopia; nystagmus; strabismus; normal color vision; and normal fundus examination. Characteristic ERG findings can help distinguish between complete X-linked CSNB and incomplete X-linked CSNB.

Cone-rod dystrophy-3 (CORD3) is an autosomal recessive, clinically heterogeneous retinal disorder with typical findings of reduced visual acuity, impairment of the central visual field, color vision deficits, and fundoscopic evidence of maculopathy, with no or few midperipheral retinal pigment deposits. Cone degeneration appears early in life with a central involvement of the retina, followed by a degeneration of rods several years later (summary by Klevering et al., 2002 and Ducroq et al., 2002). Both cone and rod a- and b-wave electroretinogram (ERG) amplitudes are reduced (Fishman et al., 2003). For a general phenotypic description and a discussion of genetic heterogeneity of cone-rod dystrophy, see 120970.

Any cone dystrophy in which the cause of the disease is a mutation in the CACNA2D4 gene.

Autosomal recessive congenital stationary night blindness is a disorder of the retina, which is the specialized tissue at the back of the eye that detects light and color. People with this condition typically have difficulty seeing and distinguishing objects in low light (night blindness). For example, they may not be able to identify road signs at night or see stars in the night sky. They also often have other vision problems, including loss of sharpness (reduced acuity), nearsightedness (myopia), involuntary movements of the eyes (nystagmus), and eyes that do not look in the same direction (strabismus).\n\nThe vision problems associated with this condition are congenital, which means they are present from birth. They tend to remain stable (stationary) over time.

X-linked congenital retinoschisis (XLRS) is characterized by symmetric bilateral macular involvement with onset in the first decade of life, in some cases as early as age three months. Fundus examination shows areas of schisis (splitting of the nerve fiber layer of the retina) in the macula, sometimes giving the impression of a spoke wheel pattern. Schisis of the peripheral retina, predominantly inferotemporally, occurs in approximately 50% of individuals. Affected males typically have 20/60 to 20/120 vision. Visual acuity often deteriorates during the first and second decades of life but then remains relatively stable until the fifth or sixth decade.

Congenital nonprogressive cone-rod synaptic disorder (CRSD) is characterized by stable low vision, nystagmus, photophobia, a normal or near-normal fundus appearance, and no night blindness. Electroretinography shows an electronegative waveform response to scotopic bright flash, near-normal to subnormal rod function, and delayed and/or decreased to nonrecordable cone responses (Traboulsi, 2013; Khan, 2014).