Conjunctival Nevus: Pigmented Spot on the Eye Surface

A conjunctival nevus is a frequent, noncancerous pigmented spot found on the conjunctiva—the clear membrane covering the white part of the eye and inner eyelids. Often detected during routine eye exams, these spots are usually harmless but may cause cosmetic concern or, rarely, signal potential eye health issues. Understanding the characteristics, causes, and management of conjunctival nevi is important for anyone noticing a pigmented spot on their eye.

What Is a Conjunctival Nevus?

A conjunctival nevus is essentially a mole on the eye's surface. It comprises a cluster of melanocytes—pigment-producing cells—forming a flat or slightly raised, brown, tan, or black spot on the conjunctiva. These nevi are similar to skin moles and are typically present from childhood or adolescence, though they may become more noticeable over time. They are most commonly located on the bulbar conjunctiva near the cornea but can occur anywhere on the conjunctival surface.

These nevi are usually unilateral (affecting one eye) and can vary in size from a few millimeters to over a centimeter. Most are stable, but some may slowly enlarge or change color during puberty or pregnancy due to hormonal influences. Importantly, the vast majority of conjunctival nevi are benign and do not require treatment beyond routine monitoring.

Causes and Risk Factors

The exact cause of this pigmented lesion is not fully understood, but it is believed to be a congenital or developmental lesion arising from melanocyte proliferation. Genetic factors likely play a role, as these spots tend to run in families. Ultraviolet (UV) radiation exposure may also contribute to the development or darkening of such nevi, similar to its effect on skin moles. Other risk factors include:

• Light skin and eye color: Individuals with lighter skin, blue or green eyes, and blond or red hair are more prone to developing conjunctival nevi.
• Age: Conjunctival nevi are often first noticed in childhood or adolescence, though they can appear later in life.
• Hormonal changes: Puberty, pregnancy, and menopause may cause existing nevi to darken or enlarge.
• Sun exposure: Chronic UV exposure is thought to increase the risk of developing pigmented lesions on the eye surface.

It's important to note that conjunctival nevi are not contagious and are not linked to any infectious agents. They are simply a benign aggregation of pigment cells.

Symptoms and Appearance

Most conjunctival nevi are asymptomatic and discovered incidentally during an eye exam. However, some patients may notice a visible spot on the eye or experience mild irritation, especially if the nevus is located near the eyelid margin or causes dryness. The appearance of a conjunctival nevus can vary:

• Color: Typically brown, tan, or black; may be uniform or speckled. Some nevi contain clear cysts, giving them a “bubbly” appearance under magnification.
• Shape: Circular or oval, with smooth or slightly irregular borders.
• Elevation: Flat (macular) or slightly raised (papular).
• Location: Most commonly on the bulbar conjunctiva near the limbus (the border between the cornea and sclera), but can also occur on the plica semilunaris or caruncle.

In some cases, a conjunctival nevus may contain visible blood vessels, which is normal. However, any sudden change in size, color, or shape, or the development of new symptoms such as pain, redness, or blurred vision, should be evaluated promptly.

Diagnosis of Conjunctival Nevus

Diagnosis is typically made during a comprehensive eye examination by an ophthalmologist or optometrist. The doctor will use a slit lamp microscope to closely examine the lesion, assessing its size, color, shape, and depth. Key diagnostic features include the presence of clear cysts within the nevus, which are characteristic of benign nevi and help distinguish them from malignant melanoma.

In some cases, the doctor may take photographs to document the lesion for future comparison. If the nevus has atypical features (e.g., irregular borders, rapid growth, or inflammation), a biopsy may be recommended. During a biopsy, a small sample of the lesion is removed and examined under a microscope to confirm the diagnosis and rule out malignancy.

Differential diagnosis includes other pigmented lesions such as primary acquired melanosis (PAM), racial melanosis, and conjunctival melanoma. Each has distinct clinical and histological features that guide management.

Treatment and Management

The majority of these nevi are benign and require no treatment. Management focuses on regular monitoring to detect any changes. Patients with stable lesions should have annual eye exams, with documentation of the lesion's appearance. Sun protection is also recommended: wearing UV-blocking sunglasses and a wide-brimmed hat can help reduce UV exposure and minimize potential changes.

If a conjunctival nevus becomes cosmetically bothersome or shows suspicious changes, treatment options include:

• Surgical excision: The nevus is removed under local anesthesia. This is both diagnostic and therapeutic, especially if there is concern for malignancy.
• Laser therapy: Certain pigmented lesions can be treated with argon or other lasers, though this is less common for conjunctival nevi due to risk of recurrence or scarring.
• Observation: For stable, asymptomatic nevi, simple observation with periodic photography is often sufficient.

After excision, the tissue is sent for histopathological examination to confirm benignity. Recurrence is rare but possible if the entire lesion is not removed. Patients should follow their ophthalmologist's recommendations for post-operative care and follow-up.

When to See a Doctor

While these nevi are generally harmless, it is important to have any pigmented spot on the eye evaluated by an eye care professional. You should schedule an appointment if you experience any of the following:

• New pigmented spot appearing on the eye surface.
• Change in size, shape, or color of an existing spot.
• Development of symptoms such as pain, redness, irritation, or blurred vision.
• Bleeding or ulceration of the lesion.
• Family history of eye melanoma or skin melanoma.

Early detection of any concerning changes is key to preventing serious complications. Regular eye exams play a vital role in maintaining eye health and catching potential issues early.

Conclusion

A conjunctival nevus is a common, benign pigmented spot on the eye surface that rarely causes problems. Understanding its typical appearance and being aware of warning signs can help individuals seek appropriate care when needed. With regular monitoring and sun protection, most people with a conjunctival nevus can enjoy excellent eye health without intervention. If you have a pigmented spot on your eye or notice any changes, consult an eye doctor for a thorough evaluation.

Remember, while the term "conjunctival nevus" may sound concerning, it is usually nothing to worry about. Knowledge and vigilance are your best tools for maintaining healthy eyes for life.