“You’re telling me I have a freckle ‘INSIDE’ my eye?!?“
If I had a dollar everytime I heard that from patients… well I sure wouldn’t be rich, but it actually does happen a lot!
A choroidal nevus (or plural nevi) are actually moles we see on the inside of the eye, and yes, they are surprisingly common occurring in about 5% of the population.
While very common, like any mole, a small percentage of nevi unfortunately develop into a melanoma. Because of this they must be carefully monitored.
Today we will talk about them… with lots of fun pictures
What is a Mole?
First, lets discuss what a nevi or mole actually is. Any freckle or mole on the body is simply a benign tumor made up of melanocytes. These melanocytes are the cells that give the skin color; darker skinned individuals have more melanocytes, littler skinned individuals less. These normal growths develop during our lives and can be a variety of colors, sizes, and can form in groups. If these moles become cancerous, they are given the term melanoma.
Other Types of Eye Moles
The human eye forms initially as an in-pouch of embryonic skin cells and since it also has melanocytes, you can also get these freckles or nevi on any part of the eye. Here’s one on the white of the eye called a conjunctival nevus, as well as a large iris nevus. These moles are easily seen in the mirror, what comes as a shock are the nevi inside the eye or choroidal nevus.
Choroidal Nevus
Choroidal nevus inside the eye can come in all shapes and sizes as well. While all nevi are by definition “normal,” they can be dark, light, small, or very, very large. The first is a relatively small mole about 1.5 mm in size, the second photo is part of a much larger that covers about a quarter of the inside of this persons eye!
What is the Risk?
The main difference between a mole on your arm and a mole in your eye is access to monitoring it. You could look at a freckle on your arm every day, however a mole in your eye we only get to see once a year. The risk of a choroidal nevus turning “bad” is about 4 in 1000 and 50% of ocular melanoma develop from existing “normal” nevi.
While the risk is relatively low, choroidal melanoma is the most common primary cancer of the eye and is something we see with unfortunate frequency. Because of this, it is important to photograph these freckles and view them through a dilated pupil every 6 months to a year.
Thanks for reading Eye to the Future and feel free to send any questions or ideas for future topics to [email protected]
Take care of those eyeballs!
Nick Wolf, OD