What Is Melanosis?
Melanosis is the accumulation of brown-black pigment on the eye due to higher presence of melanin. Ocular melanosis occurs when the eyes have black or brown pigmented areas. There are many different eye conditions that can cause melanosis. Melanin is a naturally occurring pigment that gives the skin, hair, and eyes their color. If your body produces lots of melanin then your skin, hair, and eyes will appear darker. Melanosis is usually harmless. It is common in people with darker or tanner skin complexions. In rare cases, melanosis can lead to melanoma, a type of cancer.
Types of melanosis of the eye include:
- Racial Melanosis (i.e. Limbal Melanosis)
- Conjunctival nevus
- Nevus of Ota
- Primary acquired melanosis
- Conjunctival melanoma
Key Takeaways
- Melanosis refers to the brown-black pigment on the eye’s tissues, such as on the white part of the eye.
- Melanosis of the eye is more common in people who have brown or black skin, because they have more melanin.
- Melanosis of the eye is usually not concerning. However, in rare cases, melanosis may be precancerous or cancerous.
Understanding Melanosis
Melanosis is a dark pigmentation that can happen on the eye, skin, or hair due to a high concentration of melanin. Melanin is a naturally occurring pigment in the body. Melanin makes the skin, hair, and eyes appear black or brown. For example, brown eyes contain more melanin, whereas blue eyes have less melanin. In addition to giving the skin and eyes its color, melanin protects the skin from harmful UV light that comes from the sun. Caucasians and people with lighter skin are more prone to getting skin cancer because they have lower amounts of protective melanin pigment.
When melanosis occurs, it may impact many different layers of the eye including the eyelids, conjunctiva, and uvea. Ocular melanosis means that there are areas of melanosis on the eye. Melanosis of the eye is commonly found in Asian, Indian, and African populations. It results in brown-black patches of pigment on the surface of the eye. In most cases, the patches of brown pigment are benign and pose no threat to eye health. However, in rare cases, excessive brown pigmentation indicates that the area is precancerous or cancerous. Melanosis of the eye is less common in people with light skin tones such as Caucasians and Scandanavians. If light-skinned people have melanosis of the eye, it is more likely to be cancerous or precancerous.
Non-cancerous types of eye melanosis include:
- Racial melanosis (limbal melanosis): This type of melanosis is common in people with black or brown skin and it causes a dark-brown ring around the colored part of the eye or on the white parts of the eye. The brown pigment is present in both eyes.
- Conjunctival nevus: This is a brown patch or “freckle” on the white part of the eye. A conjunctival nevus is usually only present in one eye.
Potentially cancerous types of eye melanosis include:
- Nevus of Ota: This is a brown-black pigmentation on the eye, and on the skin around the eyes. It is common in Japanese and African populations. This condition increases the risk of eye cancer and glaucoma.
- Primary acquired melanosis: These are brown patches on the eye that mostly occur in Caucasians and develop in middle age. This condition is precancerous, and 9% to 32% of people will develop eye cancer from the area that is brown.
- Conjunctival melanoma: This is an elevated brown lesion that often has blood vessels around it. A melanoma is a cancerous tumor that can spread to other areas of the body.
Symptoms Of Melanosis
- The white part of the eye may develop brown-colored patches.
- The eyelid may develop brown-colored patches.
- The skin around the eyes may become brown or darker colored.
- Either one eye or both eyes may be affected.
- The size of the pigmented area may increase over time, especially in puberty.
What Are The Causes Of Melanosis?
Common risk factors of melanosis include:
- Eye color
People with dark eye colors are more likely to get ocular melanosis. If brown areas of melanosis are present on Caucasian eyes, it is more likely to be abnormal and potentially cancerous. - Having high levels of melanin
People with dark skin, such as African or Indian populations, are more likely to get ocular melanosis because they have more melanin pigment in their bodies. - Old age
Melanosis tends to increase as we age. The brown-colored patches on the eye may grow in size. The eye doctor will typically measure the size of the brown area with the microscope to make sure it is not growing rapidly. - Hereditary
If someone in your family has melanosis, you are more likely to develop it. - Ultraviolet Rays
Excessive exposure to ultraviolet rays from the sun results in harmful consequences. One of those harmful consequences includes eye damage. Melanosis may be a sign that the eyes are responding to excess sun exposure. You should always wear sunglasses or UV protection when you are outside to prevent the structures in the eye from being sun damaged.
How Is Melanosis Treated?
The eye doctor will determine the cause of your melanosis through an eye examination and looking at the eyes under the microscope. If the doctor determines that the pigmented area of the eye is precancerous or cancerous, they may want to remove it. The following treatments may be done to remove melanosis:
- Cryotherapy, freezing away the lesion
- Laser therapy
- Surgical removal
