Ocular Albinism

Albinism is an inherited condition involving an abnormality in melanin pigment production or impairment of the maturation of melanosomes. Oculocutaneous albinism affects the eyes, skin, and hair and is an autosomal recessive disorder. Ocular albinism affects the eyes only and typically shows an X-linked inheritance pattern. It is caused by mutations in GPR143 gene.

Ocular albinism is characterised by reduced visual acuity, nystagmus, various grades of iris translucency, fundus hypopigmentation and foveal hypoplasia. Foveal hypoplasia is caused by the underdevelopment of the foveal pit and has been associated with poor visual acuity. The foveal pit and the foveal avascular zone are either reduced or absent. Another characteristic sign is chiasmal misrouting, which refers to an increased number of retinal ganglion cells from the temporal retina projecting to the contralateral hemisphere and can be detected by visually evoked potential (VEP).

Female carriers of X-linked ocular albinism type can show partial iris translucency and scattered areas of depigmentation but are otherwise asymptomatic.

Foveal hypoplasia can also occur in several conditions including achromatopsia, aniridia, microphthalmos, retinopathy of prematurity, Incontinentia pigmenti and Stickler syndrome and can also be an isolated idiopathic condition.

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