Originating from the Latin word “albus” [1] meaning white, albinism represents a set of inherited conditions characterized by absent or decreased tissue melanin in conjunction with characteristic ocular and visual pathway anomalies. Those affected by this condition manifest varying degrees of hypopigmentation and vision-related disability.

2021年9月8日 · Albinism is characterized by a genetic defect in melanin production, transport, trafficking, or maintenance. Phenotypic patterns are dependent on the level of the defect in the enzymatic pathway of melanin production. The most common types of albinism and their genetic mutations summarized below.

2023年4月13日 · Fundus hypopigmentation is reported to be present in more than 94% of individuals with albinism [Kruijt et al 2018]. Fundus examination can be performed with direct or indirect ophthalmoscopy, posterior slit lamp examination, or fundus photography.

Obligate female carriers of ocular albinism can manifest an abnormal fundus appearance due to random X chromosome inactivation (lyonization), with characteristic “mud-splatter” pigmentation on fundus examination and dark radial streaks against a bright background on fundus autofluorescence imaging.

Fundus photo of right eye (A) and left eye (B); shows clear view of choroidal vasculature due to the hypo-pigmentation of retinal pigment epithelium, pale retina, foveal hypoplasia, and indistinct optic disc margin.

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.

A man in his early 20s with cutaneous albinism was referred to an ophthalmologist for evaluation of nystagmus and photophobia. He denied oscillopsia. His best-corrected visual acuity was 20/80 OU. An anterior segment examination revealed iris transillumination defects in both eyes.

Fundus autofluorescence (FAF) is useful in these cases, as it highlights retinal pigment epithelium (RPE) changes. Areas of hyperautofluorescence indicate RPE stress, while hypoautofluorescence suggests atrophy, aiding in the identification of PCV-related abnormalities.

Oculocutaneous hypopigmentation is common to all types of HPS. The ocular manifestations are similar to that of other types of albinism. Iris transillumination defects, nystagmus, and strabismus are common features. Visual acuity is usually stable in the range of 20/40-20/300 and often accompanied by photophobia.

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.