Girl with<unk>  from Papua New GuineaThere are two principal types of<unk> : oculocutaneous, affecting the eyes, skin and hair, and ocular affecting the eyes only. There are different types of oculocutaneous<unk>  depending on which gene has undergone mutation. With some there is no pigment at all. The other end of the spectrum of<unk>  is "a form of<unk>  called rufous oculocutaneous<unk> , which usually affects dark-skinned people". According to the National Organization for<unk>  and Hypopigmentation, "With ocular<unk> , the color of the iris of the eye may vary from blue to green or even brown, and sometimes darkens with age. However, when an optometrist or ophthalmologist examines the eye by shining a light from the side of the eye, the light shines back through the iris since very little pigment is present." Because individuals with<unk>  have skin that entirely lacks the dark pigment melanin, which helps protect the skin from the sun's ultraviolet radiation, their skin can burn more easily from overexposure. The human eye normally produces enough pigment to color the iris blue, green or brown and lend opacity to the eye. In photographs, those with<unk>  are more likely to demonstrate "red eye", due to the red of the retina being visible through the iris. Lack of pigment in the eyes also results in problems with vision, both related and unrelated to photosensitivity. Those with<unk>  are generally as healthy as the rest of the population (but see related disorders below), with growth and development occurring as normal, and<unk>  by itself does not cause mortality, although the lack of pigment blocking ultraviolet radiation increases the risk of melanomas (skin cancers) and other problems. Visual problems Malian Mandinka singer Salif Keita with<unk>  Development of the optical system is highly dependent on the presence of melanin. For this reason, the reduction or absence of this pigment in people with<unk>  may lead to: * Misrouting of the retinogeniculate projections, resulting in abnormal decussation (crossing) of optic nerve fibres * Photophobia and decreased visual acuity due to light scattering within the eye (ocular straylight) Photophobia is specifically when light enters the eye, unrestrictedwith full force. It is painful and causes extreme sensitivity to light. * Reduced visual acuity due to foveal hypoplasia and possibly light-induced retinal damage. Eye conditions common in<unk>  include: * Nystagmus, irregular rapid movement of the eyes back and forth, or in circular motion. * Amblyopia, decrease in acuity of one or both eyes due to poor transmission to the brain, often due to other conditions such as strabismus. * Optic nerve hypoplasia, underdevelopment of the optic nerve. The improper development of the retinal pigment epithelium (RPE), which in normal eyes absorbs most of the reflected sunlight, further increases glare due to light scattering within the eye. The resulting sensitivity (photophobia) generally leads to discomfort in bright light, but this can be reduced by the use of sunglasses or brimmed hats.
Albinism in humans
Photosensitivity in humans
Albinism in popular culture
Coenurosis in humans
Rabies in animals
Aluminium toxicity in people on dialysis
Ciguatera fish poisoning
Cholestasis facies