Freckles and small moles are right there on the skin and can be checked periodically for any changes in size or color, but a freckle inside the eye isn’t so easy.
Nevus is a medical term for a small, pigmented and slightly raised growth on the skin. These are usually flat and benign; they typically pose no threat to us at all, but in rare cases may begin to change color or grow larger. When or if this happens, most of us know that we need to have the skin growth checked by a dermatologist, a specialist in the skin and its diseases.Nevi can also form inside the eye, usually within the choroid, the highly vascular and pigmented structure that lines the back of the eye between the retina' (the thin layer that senses light) and the sclera (often referred to as “the white of the eye”). The choroid absorbs light rays so they are not reflected and brings blood and oxygen to nourish the retina.
The choroid contains a dark pigment called melanin. Occasionally, the melanin cells clump together and form a mole or freckle in the choroid. In the general population, Choroidal nevi are quite common, but most people who have them don’t know it because the only way to see them is to examine the eye with specialized equipment.
Most of the time, Choroidal nevi do not cause any problems or affect vision at all, but about five percent of them begin to change size and appearance and may become pre-malignant, just like nevi on the skin can. The difference is that the ones on the skin are easy to monitor, but the ones inside the eye aren’t easily visible except by an eyecare practitioner.
During an eye exam, the eyecare practitioner will note any nevi, their size, shape, color and whether they are elevated. In addition, a photograph is sometimes taken of the back of the eye, both to help document the nevus and, sometimes, to show to the person who has it.
There are no symptoms and no effect on the vision by nevi, nor is there any treatment available to remove them. In the vast majority of cases, there is no need, except in the rare cases when they begin to change.
Because they cannot be monitored like freckles on the skin, people who are found to have nevi are asked to see their eyecare practitioner on a regular basis so they can be evaluated. In the case of large nevi, a patient new to the eyecare practitioner may be asked to come back more often to check it, but once the nevus has been shown not to be growing or changing, annual checkups are usually sufficient. Patients should follow the recommendation of the eyecare practitioner and schedule visits accordingly.