Birthmark in the eye, what is that?
A birthmark, or sometimes also a pigment or mole, is colloquially described as a sharply defined, benign malformation of the skin or mucous membrane. It is one of the so-called harmomas, i.e. untypically developed cell clusters and is called nevus (plural “nevi”) in the technical language. In most cases, moles are formed by pigment-forming cells, the melanocytes, more rarely also by connective tissue, blood vessel or gland cells.
At first, this is not a disease, but only a benign anomaly. In rare cases, however, it can degenerate; melanoma, a malignant tumor, can be the result. Why a birthmark degenerates is not comprehensible in most cases. However, UV radiation plays an important role in this process.
Localization and appearance
As in any other part of the body covered with skin or mucous membrane, a birthmark can also appear in the eye, more precisely on the conjunctiva, sclera, iris or choroid. If they are localized on the choroid, they can only be detected during an ophthalmological examination. A birthmark generally localized in the eye or face is called nevus ota.
Like all other moles, it often exists from birth (congenital), but can also develop later. Conjunctival nevi usually develop in the outer eyelid cleft area. They are slightly raised and have small, clear, blister-like inclusions, which may also be pigmented or unpigmented (amelanotic). During pregnancy, the pigmentation may increase due to hormonal changes.
Diagnosis
Usually the nevus ota is only a cosmetic problem. A degeneration, i.e. the transformation into a malignant tumor, is extremely rare, but very dangerous. Melanomas (called “black skin cancer” on the skin) are a very malignant form of tumors and quickly begin to spread (metastasize) to other organs.
Therefore, regular control of the birthmark is important. For this purpose, localization, size and appearance are noted in order to have a comparison at the next control examination. Especially suspicious nevi make a photo documentation necessary.
A number of special diagnostic procedures can be used to examine the birthmark in more detail. These include diaphanoscopy and fluorescein angiography, with which the ocular fundus can be better assessed. An ultrasound examination of the eye can also provide more precise information about moles of the choroid.
