What Causes Choroidal Nevus?

In the same way you may develop a freckle or a mole on your skin, similar types of spots can grow on the eye. A choroidal nevus is a growth of pigmented cells known as melanocytes that form on the eye and are often referred to as the freckle of the eye. A choroidal nevus sits on the choroid which is the middle layer of the wall of the eye just behind the retina. The retina is the innermost, light-sensitive layer of tissue in the eye responsible for sending signals from the optic nerve to the brain to relay the images that you see. The choroid supplies the outer area of the retina with the essential nutrients to maintain both the temperature and volume of the eye. 

What causes choroidal nevus? The melanocytes behind the retina are spread out evenly in the tissue. When the choroidal nevus forms, those cells clump together. Sometimes people are born with harmless, non-cancerous eye nevi. Nevus can develop both on the outside and the inside of the eye. Types of nevi outside the eye include conjunctival nevus, iris freckles and iris nevi. A conjunctival nevus is a freckle or mole-like spot on the clear film that covers the eyeball that ranges in color from yellow to brown. It is very common and not usually cancerous. Iris freckles are tiny, dark brown flecks located on the surface of the colored part of the eye. These freckles are harmless and rarely develop into melanoma. Iris nevi are similar but larger than iris freckles that grow down into the stroma or the upper layer of the iris. Although these nevi are not typically cancerous, they do grow larger over time. Choroidal nevus is the growth of nevus inside the eye. It may be gray, yellow, brown or multi-colored. During an eye exam, an ophthalmologist will check to see if it is raised, orange in color, or leaking fluid. If so, it may indicate a small choroidal melanoma. 

Beyond development at birth, the cause of choroidal nevus is generally unknown. As with skin freckles or moles, fair skinned people are more predisposed for freckles in the eye with choroidal nevus affecting 6.5% of the Caucasian population and 3-4% of the general population. There is some research to suggest that exposure to sun is a cause. For this reason, eye doctors will suggest quality sunglasses that filter UV radiation. The appearance of a choroidal nevus is not cause for concern since they are mostly harmless but should be routinely monitored by an ophthalmologist. Any changes to the nevus could indicate cancer. If you notice the eye freckle has changed shape or color, you have eye pain, you see flashing lights or if you notice any changes to your vision you should visit your eye doctor. 

If you are experiencing choroidal nevus, we encourage you to visit Associated Retina Consultants for preventative care. You will want an eye care expert to diagnose the choroidal nevus and monitor any changes that may escalate to choroidal melanoma which can be vision and life threatening. Make your eye health your top priority by scheduling your appointment at 602-242-4928 or online at WEBSITE.