Signs in ocular albinism include hypopigmentation of the fundus with clearly visible choroidal vessels, foveal hypoplasia, and hypopigmentation of the iris. Strabismus, nystagmus, photophobia, absent stereoacuity and high refractive errors including hypermetropia are other common features. Vision may be near normal but usually worse, in the range of 20/100 to 20/300. In at least some patients with ocular albinism, concentric macular rings have been identified using infrared reflectance images.
In ocular albinism there is a nearly complete crossing of nerve fibers in the optic chiasm as well as a decreased number of photoreceptors. MRI imaging of the optic chiasm in humans with albinism reveals it to be smaller with a wider angle between optic tracts, reflecting the atypical crossing of nerve fibers.
This is an X-linked recessive disorder and affects mainly men. In 80% of female carriers a mosaic of pigmentary changes can be observed in the fundus, especially in the periphery as a result of lyonization. A few female heterozygotes have ocular changes of albinism including nystagmus and reduced visual acuity, likely as a result of unequal X-chromosome inactivation. Perhaps three-quarters of carrier females have transillumination defects in the iris.
Hearing loss is often associated with pigmentation disorders and families with X-linked ocular albinism have been reported with a late onset sensorineural deafness (300650). The ocular findings are typical but deafness is not significant until late midlife.
