AlbinismGeriatric Optometry & Low Vision

M a c l e s t e r

Description

• Albinism (from Latin albus, "white“also called achromia, achromasia, or achromatosis) is a congenital disorder characterized by the complete or partial absence of pigment in the skin, hair and eyes due to absence or defect of tyrosinase, a copper-containing enzyme involved in the production of melanin. Albinism results from inheritance of recessive gene alleles and is known to affect all vertebrates, including humans.

Characteristics• Little to no melanin (important pigment) in eyes,

skin, and hair

• Vision problems are a result of the low amounts of melanin in albinos

• Eyes are usually blue or light brown, but can sometimes appear red

• Skin and hair is very pale in color

• More likely to sunburn

• Sensitivity to bright light

Causes• A person inherits one or more defective genes that

cause them to be unable to produce the normal amounts of a pigment called melanin.

• The genes are located on "autosomal" chromosomes. Autosomes are the chromosomes that contain genes for general body characteristics.

• Both parents must carry a defective gene to have a child with albinism. When neither parent has albinism but both carry the defective gene, there is a one in four chance that the baby will be born with albinism.

Types of Albinism

• Ocular Albinism (OA) affects only the eyes, not the skin or hair. It results from an X-linked chromosomal inheritance and so occurs mostly in boys.

• Oculocutaneous Albinism (OCA) affects the eyes, hair and skin and includes several different forms. The first form, OCA1 involves the tyrosinase enzyme, which converts tyrosine (an amino acid) into melanin. Melanin is a chemical that colors our skin, eyes and hair.

OCA1 two sub-groups:• OCA1a: Those with this type of albinism have no

pigment and no active tyrosinase

• OCA1b: Those with this type of albinism have some residual tyrosinase activity and so have some pigment. Although they have decreased pigmentation at birth, it may increase slightly throughout their lives. People in this group may even have the ability to sun tan.

Prevalence• United States

• An estimated 1 in 17,000 people have one of the types of albinism. Approximately 18,000 people in the United States have albinism.

• OCA 1 occurs in approximately 1 in 40,000 individuals in most populations.

Prevalence• OCA 2 is the most common type of albinism and is

especially frequent among African Americans and Africans. The estimated frequency in African Americans is 1 case per 10,000 population, while in whites, the frequency is 1 case per 36,000 population. The overall frequency is 1 case per 15,000 population across all races.

• Hermansky-Pudlak syndrome (HPS) is the most common type of albinism in Puerto Rico, with a frequency of 1 case per 2,700 population. This disorder is very rare in other parts of the world.

Mortality/Morbidity• Albinism is not associated with mortality. Lifespan is

within normal limits. Because the reduction of melanin in the hair, skin, and eyes should have no systemic effects, the general health of a child and an adult with albinism is normal. The growth and intellectual development of a child with albinism should be normal, with developmental milestones expected for age.

Mortality/Morbidity• The morbidity associated with albinism pertains to

visual impairment, skin photosensitivity, and increased cutaneous cancer risk. Patients who have syndromes associated with albinism (eg, HPS) may have hearing difficulties or abnormalities of blood clotting. Albinism also has social ramifications because patients may feel alienated as a result of the difference in appearance from their families, peers, and other members of their ethnic group.

Race• Albinism affects all persons of races.

• Parents of most children with albinism have normal eye color for their ethnic background.

• A high incidence of HPS exists among Puerto Ricans.

SexBoth males and females can be affected. However, in OA 1 (X-linked recessive OA), males are affected, while females are only carriers.

Age• All types of albinism are usually congenital.

Visual problems• Nystagmus: regular horizontal back and forth

movement of the eyes

• Strabismus: muscle imbalance of the eyes, “crossed eyes” (esotropia), “lazy eye” or an eye that deviates out (exotropia)

• Photophobia: sensitivity to bright light and glare

• People with albinism may be either far-sighted or near-sighted and usually have astigmatism

• Foveal hypoplasia: the retina, the surface inside the eye that receives light, does not develop normally before birth and in infancy

Visual problems• Astigmatism, irregular shaped cornea.

• 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 misrouting: the nerve signals from the retina to the brain do not follow the usual nerve routes

Treatment• Refractive errors should be diagnosed and treated

promptly to maximize visual acuity and minimize amblyopia.

• A comprehensive low vision examination, along with optical and non-optical low vision devices and vision rehabilitation services and training, can be helpful for some individuals with albinism.

• Absorptive sunlenses/sunglasses can reduce light sensitivity/photosensitivity.

• Glasses with prisms can decrease nystagmus and help the eyes align better; i.e., help both eyes point or look in the same direction. Prisms are special glasses that bend light and can help redirect the direction of light entering a misaligned eye.

• Surgery may also be considered to reduce nystagmus or to align the eyes, especially if either is causing a significant abnormality in head position.

• Genetic counseling can help parents and adult patients with albinism.

• Because of the decreased skin pigmentation that accompanies albinism, individuals should use hats and sunscreens and avoid excessive sun exposure to protect the skin from sunburns and skin cancer.

• Surgery may be required on the ocular muscles to decrease some of the vision problems.

Treatment of the eye conditions consists of visual rehabilitation. Vision aids, such as glasses, bifocals, prescription reading glasses, magnifiers or monoculars, colored contact lenses, bright reading lights, can help individuals with albinism.

Some people use bioptics - glasses with small telescopes mounted on. Some individuals use screen magnification products on computers.

Management• Glasses and contact lenses

• Low vision

• large-print books

• magnifying lenses

• a small telescope or telescopic lenses that attach to glasses to read writing in the distance, such as a school blackboard

• a special computer with a large screen or software that can convert speech into typing or typing into speech

Management• tablets and smart phones that allow you to magnify

the display to make writing and images easier to see 

• Blind and Partially Sighted

• making practical adaptations to your home, such as using bright colours for door frames, door handles, banisters and light switches

• specially adapted technology for people with vision problems, such as computers, landline and mobile phones 

• advice about school options for a child with vision problems 

• Photophobia

• sunglasses or tinted glasses

• Squint

• glasses or an eye patch

• Nystagmus

• surgery may be an option