Albinism occurs when one of several genetic defects makes the body unable to produce or distribute melanin, a natural substance that gives color to hair, skin, and the iris of the eye. About one in 17,000 people have Albinism.
The defects may be passed down through families.
There are two main types of albinism:
- Type 1 albinism is caused by defects that affect production of the pigment, melanin.
- Type 2 albinism is due to a defect in the “P” gene. People with this type do have a slight amount of skin coloring at birth.
The most severe form of albinism is called oculocutaneous albinism. People with this type of albinism have white or pink hair, skin, and iris color, as well as vision problems.
Another type of albinism, called ocular albinism type 1 (OA1), affects only the eyes. The person’s skin and eyes retain some color, however the retina will be affected.
Albinism is associated with the following visual difficulties:
- Reduced Visual Acuity
- Light sensitivity (Photophobia)
- Rapid eye movements (Nystagmus)
- Misaligned eyes (Strabismus)
Reduced Visual Acuity
Individuals with albinism do not have clear vision due to an underdevelopment of the central part of the retina called the macula. The macula is responsible for sharp, detail vision which works most well in bright light. The retina is very pale because of the lack of pigment.
Since eyes with albinism have insufficient pigment (melanin) to effectively absorb light, sunlight and brightly-lit environments may be uncomfortable and even painful and cause even more difficulty seeing. Individuals are often more sensitive to light coming from the sides and overhead.
In forms of vision loss that are present at birth (congenital) it is common for individuals to have an involuntary back and forth movement of the eyes called nystagmus. Individuals with nystagmus do not see the world moving, nor will their eyes appear to be moving when they look in a mirror. The only way they will notice their own eye movement will be if they see themselves in a film or video. Studies have shown that stopping nystagmus does little to improve vision. Individuals with nystagmus usually respond very well to telescopic vision aids.
The Null Point
Individuals with nystagmus will have some position of their eyes where there is the least amount of movement, called the Null point. When the eyes turn away from the null point nystagmus often increases.
While the null point is often straight ahead, sometimes it can be off to one side or above or below, causing the individual to have a head or eye turn that may appear unnatural but that provides their best vision.Children especially should be encouraged and allowed to assume whatever posture they feel provides their best vision.
Strabismus (misalignment of the eyes)
It is very common in albinism to have strabismus– either an inward (Esotropia) our outward (Exotropia) turning of the eyes. Individuals will use their preferred, dominant, eye. As the eyes do not work together depth perception (stereopsis) is absent.
Individuals with albinism almost always have high degrees of astigmatism (meaning the eye is out of round). They may also be farsighted or nearsighted. Often, despite measurements showing that there is a high prescription, individuals don’t find that conventional eyeglasses significantly improve their vision and often choose not to wear them. Not wearing glasses usually causes no worsening of the eyes.
Since albinitic eyes move back and forth (they do not see the world moving!) and as a result do not look consistently through the center of an eyeglass lens, the individual may not benefit fully from their optical correction. Since contact lenses rest on the eye and move with the eye, the individual is always benefiting from the best optical result. In individuals with high amounts of myopia, the contact lens will magnify the image a small amount which can also be helpful. There is some possibility that the lens itself may reduce the amount of nystagmus. Since there are usually high amounts of astigmatism, individuals with albinism often require rigid gas permeable (RGP) or toric soft contact lenses.
As eyeglasses by themselves usually do not offer adequate vision improvement for the individual to engage in normal visual activities, they have two remaining choices — either move close enough to see the object of regard, or bring it closer using miniature telescopes or binoculars. Individuals with albinism respond very well to telescopic magnification which can be provided as a handheld device (monocular) or a pair of eyeglasses with the telescope attached (bioptic telescope) which allows them to be hands-free. Bioptic telescopes are useful in the classroom, in social and work settings and in appropriate situations can enable the individual to be able to drive.