Blog: How Ocular Albinism Affects Vision

Albinism, also known as oculocutaneous albinism, is an inherited condition that causes lightened hair, skin, and eyes. This abnormal lightness is caused by a lack of melanin, which is a pigment that allows hair, skin, and eyes to have a darkened color. This color is a result of melanin-containing melanosomes accumulating in the basal layer of the epidermis, a layer of the skin. Melanosomes are cellular structures that normally produce and hold melanin. An individual with albinism does not have an efficient melanin production, so these melanosomes are not able to store as much melanin as they should contain.

Similar to albinism, ocular albinism is a condition that is caused by a lack of melanin production. However, ocular albinism is a disease that primarily affects the eyes, rather than the skin or hair. When an individual has ocular albinism, they experience several vision-related deficiencies. Within the eye, the fovea, which is responsible for sharp vision, is negatively affected due to the lack of melanin. This is because the fovea relies on melanin for proper development, and this pathway is disturbed in ocular albinism. Alongside decreased sharpness of vision, ocular albinism is characterized by depth perception issues, uncontrolled and rapid eye movements, and increased sensitivity to light. These symptoms are all direct results of a mutation in the GPR143 gene.

The GPR143 gene is responsible for making a protein that controls the growth of melanosomes. When this gene is mutated, it is unable to communicate with melanosomes effectively, causing a stunting of their growth. Ocular albinism is inherited in an X-linked manner because the mutated GPR143 gene is located on the X chromosome. Due to this pattern, males are far more likely to develop this condition. This is because one mutated copy of the gene in each cell is enough to cause the characteristic effects of ocular albinism in a male. On the other hand, females with two X chromosomes, and only one copy of the gene, do not experience significant abnormalities related to ocular albinism.

While oculocutaneous albinism affects up to 1 in every 20,000 people, ocular albinism only affects 1 in every 60,000 males. As mentioned above, females are much less likely to develop this condition. Ocular albinism usually occurs exclusively in males.

Currently, there is no cure for ocular albinism. While poor vision related to the condition is permanent, it usually does not become worse over time. Ocular albinism is normally diagnosed during one’s childhood, and treatments include receiving proper eye care to correct vision and using sunglasses to limit light sensitivity.

References:

https://medlineplus.gov/genetics/condition/ocular-albinism/#frequency

https://www.esighteyewear.com/vision-loss/ocular-albinism/

https://onlinelibrary.wiley.com/doi/full/10.1002/jnr.24246

https://bmcophthalmol.biomedcentral.com/articles/10.1186/s12886-021-01905-7