Albino Eye Color and How it Influences Vision

Albino Eye Color: Understanding Its Unique Appearance 

Albinism is a rare genetic defect. The condition occurs worldwide and affects people of all ethnicities.

Most people with albinism are just as healthy as anyone else. They can take specific measures to improve their quality of life, like wearing contact lenses or other optical aids.

By understanding the science behind albinism, we can challenge stereotypes, promote empathy, and reduce ignorance while appreciating the beauty of our diversity.

In this article, we’ll explore albinism at length, including the following:

• Types and prevalence of albinism
• The genetics of albinism
• How albinism influences eye color
• Ocular challenges of people with albinism

What is Albinism?

Albinism is a genetic disorder caused by gene mutations in melanin production. Melanin is responsible for eye, skin, and hair color.

Most cases of albinism are hereditary, meaning the albinism genes are passed from parent to offspring. People with oculocutaneous albinism (OCA) usually have little or no melanin in their skin, hair, and eyes.

Lack of melanin pigment causes these body parts to appear white or pale. Sunburn is one of the most common complications of albinism.

How Prevalent is Albinism?

Albinism affects about one in every 18,000 to 20,000 people in the United States and one in 3,000 people globally.² There is no cure for albinism, but people with the condition can take steps to protect their hair, skin, and eyes.

Albinism and Pigmentation

Lack of pigmentation due to low melanin production is the major physical sign of albinism. People with albinism will have the following characteristics:

• Pale skin
• Light blonde, brown, reddish, or white hair
• Light eye colors like pink, light blue, green, gray, or light brown.

Lack of melanin pigmentation on skin and eyes poses a danger of sun damage since darker shades provide better protection against harmful UV rays.

Ocular Challenges for People with Albinism

The lack of melanin in the eyes directly affects vision quality. Most people with albinism may need vision aids to improve their quality of life.

Albinism and Vision

Ocular albinism is also associated with vision issues such as:

• Myopia (short-sightedness)
• Hyperopia (long-sightedness)
• Poor depth perception (not being able to see things in three dimensions)
• Misrouting of the optic nerve (affects nerve signal transmission)
• Reduced visual acuity 
• Rapid, involuntary eye movements called nystagmus
• Eyes that look in two different directions (strabismus)
• Light sensitivity

Although vision loss is permanent, it does not worsen over time and can be managed with prescription reading glasses or contact lenses. 

Eye Movement Anomalies

A common eye problem in albinism is the rapid and uncontrollable back-and-forth eye movement that affects vision quality. This condition is known as nystagmus.

You may notice some affected individuals tilting their heads or assuming an uncommon head position to see better. 

How Does Albinism Influence Eye Color?

Albinism affects eye color because it’s associated with a lack of melanin, the substance responsible for eye color. 

Absence of Pigmentation in Eyes

Eyes with less melanin absorb less light and reflect more light. When light hits such eyes, it splits into various colors in a process called Rayleigh scattering. 

Most people with albinism have blue, hazel, green, or light brown eyes, depending on the amount of melanin pigmentation. Some people may appear to have red or violet eyes since the lack of melanin allows underlying blood vessels to show.

Variability in Eye Colors

The amount of melanin in your iris will determine your eye color. Brown eyes have more melanin, whereas blue, red, and other color variations have less melanin.

Since melanin protects eyes against sun damage, it’s worth noting that people with color variations other than brown are at a higher risk of UV exposure.

Different Types of Albinism

There are two main types of albinism based on the parts affected by insufficient melanin production:

Oculocutaneous Albinism

Oculocutaneous albinism (OCA) is the most common form of albinism, affecting 1 in 7 people.⁵ It affects the skin, eyes, and hair pigmentation.

There are seven types of oculocutaneous albinism (OCA1 to OCA7). The most common subtypes globally are OCA1 (1 in 40,000 people) and OCA2 (1 in 39,000).

Ocular Albinism

Ocular albinism (OA) is a rare form that mainly affects the eyes. It reduces pigmentation of the iris (the colored part of the eye) and the retina, the part responsible for capturing light signals and transmitting them to the brain for interpretation.

Ocular albinism affects more males (1 in 60,000) than females due to the inheritance pattern (X-linked inheritance).⁶

Rare Syndromes Associated with Albinism

Some cases of albinism are associated with rare hereditary syndromes. These include:

• Hermansky-Pudlak syndrome. Patients present with OCA in addition to bleeding and bruising problems, bowel disease, and lung issues.
• Chediak-Higashi syndrome. Patients present with OCA alongside immune problems, infections, bleeding disorders, and nervous system issues. 
• Griscelli Syndrome (GS). Also known as partial albinism with immunodeficiency. Patients present with pigmentary dilution of the skin and hair with clumps of pigment in hair shafts (accumulated melanosomes in melanocytes).
• Elejalde Syndrome (ES).⁷ Patients present with silvery hair and severe central nervous system (CNS) dysfunction.
• Cross-McKusick-Breen Syndrome (CMBS). Patients present with pale skin, blonde hair with a yellow-gray metallic sheen, cloudy cornea, and other ocular anomalies.

The Genetic Aspects of Albinism

Scientists have linked albinism to mutations in the following genes involved in melanin production: 

• TYR gene. A mutation causes oculocutaneous albinism type 1(OCA1) 
• OCA2 (formerly P-gene). A mutation causes oculocutaneous albinism type 2(OCA2)
• TYRP1. A mutation causes oculocutaneous albinism type 3(OCA3)
• SLC45A2 (MATP). A mutation causes oculocutaneous albinism type 4(OCA4)

Autosomal vs. X-linked Recessive Inheritance

Autosomal recessive inheritance is an inheritance pattern. It occurs when two parents pass a copy of the albinism gene to their child.

If both parents carry the gene for albinism, there is a 1 in 4 chance of bearing a child with the condition.³  If only one parent passes the mutated gene, the child will be a carrier and show no signs of albinism. However, they can pass on the variant gene to their offspring.

X-linked recessive inheritance occurs when a carrier mother passes the albinism gene to her son. This inheritance pattern can’t occur between a father and son because the son only inherits his father’s Y chromosome.

Ocular Albinism and X-Linked Recessive Inheritance

Ocular albinism (OA) can be inherited from a parent through  X-linked recessive inheritance. Unlike oculocutaneous albinism (OCA), which affects the eyes, skin, and hair, OA only affects the eyes.

The mutated gene in ocular albinism is passed on from a carrier mother to her son.⁴ Males are more likely to manifest signs of X-linked ocular albinism because they only have one X chromosome, whose mutation is sufficient to cause the condition.

Summary

• Albinism is a genetic disorder caused by mutations of certain genes involved in melanin production. 
• Most cases of albinism are hereditary, meaning the albinism gene is passed from parent to offspring. 
• The two main types of albinism are Oculocutaneous albinism (OCA) and ocular albinism (OA)
• Most cases of albinism are passed to offspring in an autosomal recessive inheritance pattern. However, X-linked inheritance is possible, especially in ocular albinism.
• Understanding the science behind albinism is important in creating a comfortable environment for people with the condition while appreciating the beauty of human diversity.