A conjunctival nevus is a common, benign spot on the conjunctiva, the clear membrane covering the white of the eye. Often called an “eye freckle,” it is similar to a mole on the skin. These spots are composed of melanocytes, the same cells that produce pigment in the skin, and can vary in color. They typically appear during childhood or early adulthood.
Appearance and Characteristics
A conjunctival nevus most often appears on the bulbar conjunctiva, in the area between the eyelids exposed to the environment. The color can range from light yellow-brown to dark brown, and some nevi may lack pigmentation, appearing as a clear or slightly yellow spot. They are flat or only slightly elevated from the surface of the eye.
A defining feature that helps identify a conjunctival nevus is the presence of small, clear pockets within the lesion. These structures are intralesional epithelial cysts. The existence of these tiny, transparent cysts is a strong indicator of a benign condition, as they are rarely found in malignant lesions. Hormonal shifts during puberty or pregnancy can sometimes cause them to darken, which may give the false impression of growth.
Diagnosis and Monitoring
The diagnosis of a conjunctival nevus is made by an ophthalmologist or optometrist during a comprehensive eye examination. The primary tool used is a slit lamp, a high-powered microscope that allows the doctor to view the eye’s structures in great detail. This instrument enables inspection of the lesion’s size, shape, color, thickness, and the presence of features like cysts.
To establish a baseline, the standard of care involves photographic documentation. Taking precise photographs allows the eye care professional to accurately track any changes over time. In some ambiguous cases, anterior segment optical coherence tomography (AS-OCT) may be used to get a cross-sectional view and confirm the presence of cysts not visible with the slit lamp.
Distinguishing From Melanoma
While the vast majority of conjunctival nevi are harmless, they have a low risk—less than 1%—of transforming into a malignant melanoma. Because of this potential, careful monitoring for specific warning signs is part of long-term care. An eye doctor will look for significant changes from baseline photographs, such as a noticeable increase in the lesion’s size or thickness. These changes could signal a vertical growth phase, a characteristic of melanoma.
Other suspicious features include changes in coloration, particularly multiple different shades (variegated pigmentation), or bleeding. The appearance of prominent, new blood vessels leading to the lesion, known as feeder vessels, is another concerning sign. A nevus should be movable over the underlying white sclera; if it becomes fixed, this could indicate deeper invasion. Any pigmented lesion in less common locations, like the conjunctiva lining the eyelids, is also considered atypical.
Management and Treatment
For a conjunctival nevus that remains stable and shows no suspicious features, the standard management is periodic observation. Regular check-ups with an eye care professional are sufficient to ensure the lesion remains benign. No active treatment is necessary.
If a nevus shows worrisome changes, such as growth or new vascularity, or if it causes persistent irritation, surgical removal is recommended. The procedure involves a complete excisional biopsy, where the entire lesion is removed with a safety margin of surrounding healthy tissue. The removed tissue is then sent to a pathology laboratory for examination to determine if it is benign or malignant.