Like a raised freckle on the skin, nevi can also occur inside your eye. The most common choroidal nevus are unusual and can only be seen by a dilated eye examination. Like a nevus on the skin, a choroidal nevus can grow into a malignant melanoma. This is why it is important to be followed on an annual basis as these can lay dormant for 10 years and suddenly develop into a malignant melanoma.
A choroidal nevus rarely requires treatment. Photography is typically used to document the size of a choroidal nevus. If the nevus has an orange pigmentation, is leaking fluid, or is 2 mm or greater in size, it may become a malignant choroidal melanoma.
Depending upon its appearance, patients with a choroidal nevus should have their eyes examined at least every year. Currently, photography and fluorescein angiogram are valuable tools with examination to assess whether or not the nevus has changed over time or whether it is developing vascularity, which may be leaking. If the choroidal nevus has orange pigment or has thickened, it should be checked more often. If a choroidal nevus is leaking subretinal fluid, this is a particularly ominous sign. Such tumors should be followed more closely for evidence of growth or malignant transformation into a choroidal melanoma.
It is reasonable to have a retinal specialist or ophthalmologist check your choroidal nevus to see if it looks suspicious. This examination may include the use of ultrasonography, specialized photography, such as fluorescein angiogram, and optical coherence tomography (OCT) testing. It is a good idea to keep a picture of your choroidal nevus so that, if you were to transfer ophthalmologists or retinal specialists from one are of the country to another, you have a baseline by which a new examination can be compared. This picture can therefore be compared to future examinations to help determine if the nevus has changed or stayed the same.
Rarely a choroidal nevus can leak or be associated with the growth of abnormal blood vessels. These changes can cause a localized retinal detachment/degeneration, flashing lights, and loss of vision. A typical choroidal nevus is asymptomatic, causing no symptoms, and is usually found on a routine dilated examination with ophthalmoscopy.
A choroidal nevus is usually a pigmented tumor of the blood vessel layer called the choroid, which is beneath the retina. A choroidal nevus is typically grey but can be brown, yellow, or variably pigmented. Examination will reveal whether or not the choroidal nevus is raised, meaning it has thickness, or whether there is orange pigment called lipofuscin, or is leaking fluid, which is called subretinal fluid. If the choroidal nevus has one or more of these findings, it is labeled as a suspicious choroidal nevus that might manifest into a small choroidal melanoma.
A choroidal nevus can also have yellow-white dots on the surface called drusen. This is a sign that the choroidal nevus is preventing the eye from removing retinal waste products. It is also a sign that the choroidal nevus has been present for a long enough time for those waste products to accumulate. There are no studies to show how long it takes for drusen to form on a choroidal nevus.
Treatments for a benign choroidal nevus are not required. There is no way to safely remove them. Since the choroidal nevus can turn into a choroidal melanoma, it is recommended to have it periodically checked by a retinal specialist.
The differential diagnosis of choroidal nevi can be congenital hypertrophy of the retina pigment epithelium combined, hamartomas of the retina pigment epithelium, choroidal metastases, or choroidal hemangiomas. The differentiation of this is usually done by a retinal specialist. Followup is advised even though calculations of Ganley and Constock in the American Journal of Ophthalmology, 1973, showed that only 1 of 500 patients with choroidal nevi will develop a malignant change in a 10-year period.
A suspicious nevi usually has the presence of two of the following features:
- Largest diameter is between 2 and 5 disc diameters.
- Thickness is from 1-2 mm.
- There is a significant effect on the overlying structures with most important being the presence of orange pigment on the tumor surface.
The presence of subretinal fluid and visual field defects is of little significance.