A choroidal nevus is a pigmented spot that forms in the choroid, the layer of blood vessels beneath the retina. Similar to a freckle or mole in the eye, these nevi are often discovered during a routine eye exam. Most are harmless, but in rare cases, they may develop into choroidal melanoma, making regular monitoring essential.
A choroidal nevus can appear grayish, brown, or yellowish and may vary in size. Since these eye freckles usually do not cause noticeable symptoms, many people remain unaware of their presence. Understanding the potential risks associated with a choroidal nevus is the first step in maintaining long-term eye health.
Understanding Choroidal Nevus
A choroidal nevus is composed of melanocytes, the same pigment-producing cells found in skin freckles and moles. These lesions typically remain stable over time, but in rare cases, they can grow or develop features that suggest malignancy.
Types of Choroidal Nevus
Choroidal nevi are classified based on their appearance and characteristics:
1) Halo Choroidal Nevus
A halo choroidal nevus is characterized by a pigmented central lesion surrounded by a depigmented or lighter-colored ring. This halo effect occurs due to the body’s immune response, which can cause atrophy of the surrounding retinal pigment epithelium. These nevi are usually benign and stable, but regular monitoring is essential to detect any changes that may indicate malignant transformation.
2) Giant Choroidal Nevus
A giant choroidal nevus is an unusually large pigmented lesion, typically measuring more than 10 mm in diameter. Due to its size, it may carry a slightly higher risk of growth or transformation into melanoma compared to smaller nevi. Patients with giant nevi should undergo periodic eye exams, including imaging techniques such as optical coherence tomography (OCT) and ultrasonography, to assess any suspicious changes over time.
3) Choroidal Nevus with Drusen
A choroidal nevus with drusen features the presence of small yellowish deposits on its surface, which are composed of accumulated metabolic waste products. The presence of drusen suggests that the nevus has been stable over time, as they form gradually due to chronic retinal pigment epithelium changes. These nevi are typically low-risk for malignancy, but ongoing observation remains important to rule out any potential complications.
Differences Between a Choroidal Nevus and a Melanoma
| Feature | Choroidal Nevus | Choroidal Melanoma |
| Size | Usually ≤5 mm in diameter and <2 mm in thickness | Typically >10 mm in diameter and >2 mm in thickness |
| Growth | Generally stable over time | Progressive growth over months or years |
| Color | Grayish or brown with well-defined borders | Dark brown, orange, or variable pigmentation with irregular borders |
| Surface Features | Flat or slightly elevated; may have drusen | Elevated, dome- or mushroom-shaped; may have orange pigment |
| Presence of Fluid | Rarely associated with subretinal fluid | Frequently has subretinal fluid accumulation |
| Symptoms | Usually asymptomatic; rarely affects vision | May cause vision loss, flashes, floaters, or visual distortions |
| Risk of Malignancy | Low risk of transformation | High potential for metastasis if untreated |
| Monitoring | Routine observation with eye exams and imaging | Requires immediate evaluation and possible treatment, including radiation or surgery |
Regular monitoring of a choroidal nevus is essential to detect early signs of transformation into choroidal melanoma. If any suspicious changes occur, prompt medical evaluation is crucial.
Symptoms of a Choroidal Nevus
Most people with a choroidal nevus experience no symptoms. However, in some cases, it may cause:
- Blurred vision, flashes of light, or visual field disturbances if it affects the retina.
- Metamorphopsia (visual distortion) or blind spots in rare cases.
- Floaters (tiny specks drifting across your vision) associated with the nevus.
- Eye discomfort or pressure if the nevus impacts surrounding tissues.
- Peripheral vision loss in advanced cases affecting retinal function.
- Changes in color perception, indicating potential impact on the macula.
- Night vision problems due to interference with the choroidal blood supply.
- Sudden flashes of light or a curtain-like shadow, which could indicate retinal detachment requiring immediate medical attention.
When to Be Concerned
If a choroidal nevus is accompanied by any of the above symptoms, an immediate eye exam is recommended to rule out complications.
What Causes a Choroidal Nevus?
The exact cause of a choroidal nevus is not fully understood, but contributing factors may include:
- Genetics – Similar to skin moles, genetics play a role.
- Sun exposure – Some studies suggest a possible link between UV light and eye pigmentation changes.
- Pigmented cell accumulation – The natural development of melanocytes in the choroid.
- Hormonal changes – Puberty, pregnancy, or menopause may influence its appearance.
- Aging – Eye pigmentation can change with age.
- Underlying health conditions – Certain inflammatory diseases may contribute.
- Environmental factors – UV radiation or pollution might affect pigmentation in the eye.
Risk Factors
Several factors may increase the likelihood of developing a choroidal nevus:
- Age – More common in adults, especially as they get older.
- Genetics – A family history of ocular conditions may increase risk.
- Fair Skin & Light Eyes – People with lighter skin tones may be more prone.
- Sun Exposure – Long-term exposure to UV radiation may contribute.
- Immune System Disorders – Some studies suggest a link between immune irregularities and ocular pigmentation changes.
- Eye Trauma – Previous eye injuries might trigger pigmentation changes.
- Hormonal Fluctuations – Life stages like puberty, pregnancy, or menopause may influence growth.
- Medical History – Having other moles (nevi) on the skin could indicate a higher likelihood of developing a choroidal nevus.
Diagnosis and Tests
A choroidal nevus is typically detected during a comprehensive eye exam. Your eye doctor may perform the following tests:
- Dilated Eye Exam – Provides a clear view of the back of the eye.
- Fundus Photography – Helps track changes in size, shape, or color over time.
- Optical Coherence Tomography (OCT) – Produces detailed images of the retina and choroid.
- Ultrasound Imaging – Determines the nevus’s size, shape, and elevation.
- Fluorescein Angiography – Detects abnormal blood flow to rule out malignancy.
- Autofluorescence Imaging – Highlights metabolic activity to differentiate between benign and potentially malignant nevi.
- Genetic Testing – Assesses the risk of the nevus turning cancerous.
- Visual Field Testing – Checks for peripheral vision loss due to complications.
Early detection and regular monitoring are essential to prevent complications.
Treatment and Management
If a choroidal nevus shows growth, fluid leakage, or malignant features, the following treatments may be considered:
- Laser Therapy – Used to destroy abnormal cells if malignancy is suspected.
- Radiation Therapy – Applied in early cases of choroidal melanoma.
- Surgical Removal – Rarely needed but performed if the lesion is causing significant visual disruption.
- Photodynamic Therapy (PDT) – Uses a photosensitizing agent and laser light to target abnormal cells.
- Anti-VEGF Therapy – If the nevus is associated with choroidal neovascularization, anti-VEGF injections may help prevent vision loss.
Living with a Choroidal Nevus
Most people with a choroidal nevus live normal lives. Regular eye check-ups are the key to ensuring eye health.
- Emotional Impact – Learning that a nevus is benign can bring peace of mind.
- Children & Choroidal Nevus – Though rare in children, early detection is essential.
- Technological Advances – Cutting-edge imaging tools improve diagnosis and monitoring.
- Support Networks – Connecting with others can provide reassurance and practical tips.
- Healthy Eye Habits – Wearing UV-protective sunglasses, maintaining a balanced diet, and avoiding smoking contribute to overall eye health.
Conclusion
A choroidal nevus is a common, usually harmless eye condition that requires vigilance, not fear. Understanding its symptoms, causes, and management is crucial for eye health.
Regular eye exams are essential for early detection and monitoring. If you or someone you know has a choroidal nevus, encourage routine follow-ups and stay informed about ocular health.
FAQs
Is a choroidal nevus cancerous?
Most choroidal nevi are benign and never turn cancerous, but regular monitoring helps detect any potential changes early.
How often should a choroidal nevus be checked?
Your eye doctor may recommend follow-up exams every 6 to 12 months, depending on the nevus’ size and characteristics.
Can a choroidal nevus cause vision loss?
In rare cases, if the nevus affects the retina or causes fluid buildup, it could impact vision.
Are there any lifestyle changes that can help prevent complications?
Yes! Maintaining a healthy lifestyle with good nutrition, regular exercise, and proper eye care can support overall ocular health and reduce the risk of complications.
What should I do if my choroidal nevus changes in appearance?
If you notice changes in the size, shape, or color of your nevus, contact your eye doctor immediately for a comprehensive exam.
