What is a choroidal nevus?

A choroidal nevus is a flat, pigmented spot in the choroid — the blood-vessel layer under the retina — essentially a freckle inside the eye. Most cause no symptoms, do not affect vision, and never cause trouble. But like a skin mole, a small percentage can transform into choroidal melanoma over time, so a nevus should be photographed and measured, then re-examined periodically — typically every 6–12 months at first — watching for growth, orange pigment, or fluid under the retina. If you have been told you have one, keep those monitoring visits even though you feel nothing.