Choroideremia (CHM) is an X-linked recessive eye disease causing degeneration of the choriocapillaris, retinal pigment epithelium, and photoreceptors, leading to severe visual impairment by adulthood. The pathogenetic mechanisms are unknown. The first clinical manifestation in CHM is night blindness during early adulthood followed by reduction of central vision and constriction of visual fields. The choroid and retina undergo complete atrophy. Heterozygous female carriers have no visual defect but often show striking funduscopic changes such as irregular pigmentation and atrophy around the optic disc.