Choroidal Nevus

The eye is like a camera. There are lenses in the front of the eye which focus light onto the back of the eye. The light is focused onto a thin light sensitive membrane in the back of the eye known as the retina. The retinal is like the film in a camera. The retina has one of the highest demands for oxygen per square millimeter of any tissue in the body. To satisfy this high demand for oxygen, the retina sits on top of a very vascular membrane known as the choroid. The choroid contains pigment cells. Occasionally these pigment cells may clump together forming a freckle. This tends to occur more commonly as people get older and is similar to aging spots on the skin. These freckles of pigment in the choroid are known as choroidal nevi.

Choroidal nevi are common. When followed for many years over 5% of choroidal nevi may grow in size. If the nevi occur beneath the macula, the central area of the retina responsible for fine vision, they may cause some distortion and blurring of vision. Nevi in many ways are similar to freckles on the skin. Freckles on the skin very rarely can develop into a cancer known as a melanoma. When this happens the freckle may grow in size or change color. A similar change may occur to choroidal nevi. If this happens the nevus may need to be treated or studied in order to determine if it has turned into a cancer.

Freckles on the skin are easy to see and follow. Choroidal nevi cannot be seen unless your eye doctor looks into the back of the eye. For this reason, people with choroidal nevi are usually asked to see their eye doctor on a regular basis so that any growth or changes can be studied further. Your eye doctor may wish to have photographs taken of the nevus for future comparison.

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