What Is a Nevus?
A nevus is a common, colored growth on or in your eye. Sometimes called a freckle of the eye, it is similar to a mole on your skin. A nevus (plural: nevi) can be in the front of your eye, around the iris, or under the retina at the back of the eye.
What Causes Nevi?
A nevus is made up of cells called melanocytes. These cells produce melanin, the pigment that colors our hair, skin and eyes. Most of the time, melanocytes are spread evenly throughout body tissue. Sometimes, though, these cells can clump together and form nevi.
People can be born with harmless eye nevi. A pigmented spot that develops later in life is usually harmless as well, but may have a greater risk of becoming cancer.
An eye nevus needs to be watched regularly by an ophthalmologist because, like a skin mole, it could possibly develop into cancer of the eye.
There may be an association between exposure to ultraviolet (UV) light and developing nevi. Wearing sunglasses that protect your eyes from UV light is always recommended.
Nevus on the Outside of the Eye
A nevus or eye freckle that can be found on the outside of the eye include the following types:
- Conjunctival nevus. A conjunctival nevus is a freckle or mole-like spot on the clear film (conjunctiva) covering your eyeball. This nevus is a very common type. It ranges from yellow to brown, and it can lighten or darken over time. It is usually not cancerous. However, your ophthalmologist will watch it over time, and if it grows larger, they may check it to see if it becomes a type of cancer called melanoma.
- Iris freckles. Iris freckles are tiny, dark brown flecks on the surface of the colored part of the eye (iris). Like skin freckles, they are caused by a buildup of melanin pigment. They are harmless and usually do not develop into melanoma.
- Iris nevi. Like iris freckles, iris nevi are dark spots on the colored iris. However, iris nevi are larger than iris freckles, and they grow down into a part of the iris called the stroma. Iris nevi grow larger with time. Like iris freckles, these nevi are usually benign (not cancerous). However, an ophthalmologist will monitor them over time for any changes.
You can see both iris freckles and iris nevi with the naked eye, but an ophthalmologist will do an eye exam to determine which type you have.
Choroidal Nevus: Nevus Inside the Eye
A nevus inside the eye is called a choroidal nevus. It is found under the retina in a layer of tissue called the choroid. A choroidal nevus can only be seen during an eye exam. A choroidal nevus may be gray, yellow, brown or have multiple colors. Your ophthalmologist will check to see if it is raised, is orange colored, or is leaking fluid. Any of these findings means it could be or become a small choroidal melanoma.