Nevus means mole. A nevus is a colored growth, like moles on the skin, and occurs on or in the eyeball. Nevi, the plural for nevus, can grow on the front part of the eyeball, around the iris and even at the back of the eye under the retina.
Conjunctival nevus, iris freckles and iris nevi are common and easy to spot. A choroidal nevus is only evident during an eye exam.
Nevus is generally not cancerous, but the eye doctor should keep an eye on it.
Also Known As
- Conjunctival nevus - It is a mole like spot or a freckle on the conjunctiva (the transparent tissue covering the eye)
- Iris freckles – These are tiny, dark brown harmless freckles on the surface of the iris (the colored part of the eye)
- Iris nevi – These are dark spots on the iris. They are larger than iris freckles and grow more prominent over time. They spread down into the deeper layers of the iris, like the stroma.
- Choroidal nevus – It is a nevus inside the eyeball. It grows in the choroid (the tissue under the retina)
Causes and Risk Factors
Melanocytes, the melanin-producing cells make nevi. These specialized cells give color to the skin, hair and eyes. They are well spread out throughout the body. Nevus forms when they buildup or clump together.
Nevi can be brown, yellow, gray or a combination of colors. Some forms of nevi occur before birth. Iris freckles often develop in older people.
Researchers are yet to understand why some people have them and others don’t. Risk factors include:
- Race – Choroidal nevi are more common in white people.
- Exposure to the sun UV rays
Signs & Symptoms
Often, a conjunctival nevus appear as a visible freckle on the eye white. They remain stable and have no other symptoms. The nevi may change color with time, especially in women during puberty or pregnancy.
Iris nevi are more common in people with blue eyes and can be spotted through eye exams.
Choroidal nevi are asymptomatic, i.e. present no symptoms.
A person should see an eye doctor if:
- An eye freckle has grown
- A nevus has changed its color or shape
- Has eye pain
- Sees flashing lights
- There are changes in vision
The eye care professional can identify a nevus during a routine eye exam. At times, he/she may use imaging techniques such as OCT to examine a nevus like choroidal nevus more closely.
They will want to see if the nevus is orange in color, raised and has abnormal blood vessel growth or there is fluid leakage. These findings could mean it may become or is a choroidal melanoma.
The eye professional may recommend checkups every six months to see if there are changes in the nevus. The checkup frequent may become annual or once every two years where the nevus shows no difference.
Treatment is aimed towards remedying the underlying issue.
The eye doctor recommends treatment only where a nevus becomes cancerous.
Treatment options include:
- Watchful waiting - Where the cancer treatment side effects can be more problematic than helpful.
- Targeted drugs
- Immunotherapy drugs
In advanced cases, treatment may involve laser therapy, radiation, surgery or removal of the eye.
The eye surgeon can also remove the nevus where there is suspicion of melanoma, presence of melanoma or complications. Depending on the situation, the surgeon may use argon laser therapy or surgery.
On rare occasions, it may be necessary to remove a nevus on the outer eyewall when it affects the appearance of the eye.
A nevus can change to melanoma with age. One that develops later in life is at a greater risk of becoming an eye cancer.
Choroidal nevi can also cause retinal detachment or loss of vision.
Even though most nevi are benign, regular checkups every six months to a year are highly recommended. The doctor will track them and document any changes in color, size or shape.
Wearing sunglasses with UV protection when outdoor blocks the harmful rays from reaching the eyes. It may lower the chances of a nevus turning into melanoma.
It also reduces the chances of developing other serious eye problems such as cataracts.