Choroidal Naevus | Eye Health Conditons

What is a Choroidal Naevus?

A choroidal naevus (pronounced “nee-vus”) is a flat or slightly elevated pigmented spot found within the choroid, the layer of blood vessels beneath the retina. These growths are benign (non-cancerous) and made up of pigmented cells called melanocytes—similar to a mole on the skin, but located inside the eye.

Choroidal naevi are quite common, especially in Caucasian individuals, and are often discovered by chance during a routine eye exam. Studies suggest that up to 10% of Caucasians may have a choroidal naevus, and most of them never cause any symptoms or problems.

Although generally harmless, it’s important to monitor choroidal naevi regularly to ensure they do not develop suspicious features that could indicate transformation into a rare eye cancer called choroidal melanoma.

ARRANGE A CONSULTATION GIVE US A CALL

What is a Choroidal Naevus?

ARRANGE A CONSULTATION GIVE US A CALL

How Are Choroidal Naevi Detected?

In most cases, a choroidal naevus is discovered incidentally during an eye test carried out by an optometrist. Since these lesions are usually asymptomatic, they can easily go unnoticed without a dilated retinal exam.

Once detected, patients are typically referred to a specialist ophthalmologist or retinal specialist for further investigation and baseline imaging.

Do Choroidal Naevi Cause Any Symptoms?

In the vast majority of cases, choroidal naevi do not cause any symptoms. However, if the lesion is located close to the macula (the part of the retina responsible for detailed central vision), it could lead to subtle visual changes or distortions in rare cases.

You should seek specialist review if you experience:

Blurred or distorted vision
Sudden appearance of floaters or flashes
A dark spot in your central vision

Even though these symptoms are uncommon in patients with naevi, they should never be ignored.

How Is the Risk of Melanoma Determined?

Although most choroidal naevi are harmless, a small percentage may transform into a malignant melanoma. To help assess this risk, a scoring system developed by The Royal College of Ophthalmologists is used. The naevus risk score ranges from 0 to 10, with higher scores indicating a higher risk of malignancy.

Here’s how the scoring works:

Score 0/10 – Common naevus

→ Can usually be monitored by an optometrist with no need for referral.
Score 1/10 – Low-risk naevus

→ Can be monitored by either an optometrist or an ophthalmologist.
Score 2/10 – High-risk naevus

→ Requires regular follow-up by a specialist ophthalmologist.
Score 3/10 or more – Probable melanoma

→ Urgent referral to an ocular oncologist is required.

How Are Choroidal Naevi Investigated?

To fully understand and safely monitor a choroidal naevus, your ophthalmologist may perform several tests, including:

1. Colour Fundus Photography

Widefield imaging provides a detailed colour photograph of the retina and helps track any growth or pigment changes over time.

2. Autofluorescence Imaging

This test uses special lighting to highlight metabolic changes in the retina. It can help identify if the naevus is affecting the surrounding tissue or leaking fluid.

3. Optical Coherence Tomography (OCT)

A high-resolution scan that shows cross-sectional images of the retina. It helps detect if there’s fluid, retinal swelling, or thinning associated with the lesion.

4. Ultrasound B-Scan

Similar to pregnancy ultrasound, this test uses sound waves to measure the size and thickness of the lesion. Larger or thicker naevi are more likely to need close follow-up.

What Is the Risk of Cancer?

The estimated lifetime risk of a choroidal naevus turning into a choroidal melanoma is less than 1 in 5,000. That means the vast majority of these lesions will never become cancerous, especially if they remain small, flat, and unchanged over time.

Key features that may suggest higher risk include:

Growth over time
Fluid or subretinal leakage
Orange pigment on the surface of the naevus
Location under the macula
Greater thickness on ultrasound

Do I Need Treatment?

Most people with choroidal naevi do not need treatment. Instead, they are monitored over time to ensure there are no suspicious changes.

If your naevus shows signs of growth or begins affecting the retina, your eye specialist may suggest more frequent monitoring or refer you to an ocular oncology unit for further evaluation.

FREQUENTLY ASKED QUESTIONS

+ What tests are done for choroidal naevi?

It is wise to investigate pigmented lesions in the eye to understand them fully. Common tests that are done include:

Colour photography (especially widefield images) – this can help spot changes over time
Autofluorescence imaging – this is a bright light photograph of the retina
OCT scanning – this is a test that can image the retina in great detail
Ultrasound B scan – this is similar to the test done on pregnant women to check the health of the baby

+ What is the MOLES score?

This is a scoring system that helps identify choroidal naevi that may become cancerous. The scoring is out of 10. The Royal College of Ophthalmologists classifies naevi based on this score:

Score 0 out of 10: common naevus – can be monitored by the optician
Score 1 out of 10: low risk naevus – can be monitored by optician or ophthalmologist
Score 2 out of 10: high risk naevus – monitoring by ophthalmologist
Score 3 out of 10: probable melanoma – referral to ocular oncologist

+ How is a choroidal naevus managed?

Most choroidal naevi will never cause a problem. The estimated risk of becoming cancerous is less than 1 in 5,000 so they can be safely monitored by an optician. Should they have any features that increases this risk, they will need monitoring by an ophthalmologist. Only a very small group of naevi are deemed high risk. These will need more close monitoring or possibly even referral to an ocular oncologist.

+ Are choroidal naevi dangerous?

No, they are generally benign and do not cause symptoms. But they should be monitored regularly to check for any signs of transformation.

+ How often should I have my choroidal naevus checked?

This depends on the size and score of the naevus. Your ophthalmologist or optometrist will recommend the appropriate schedule—usually annually for low-risk naevi.

+ Can a naevus be removed?

In almost all cases, no treatment or removal is necessary. If it becomes malignant, then management may involve radiotherapy or surgery.

+ What’s the difference between a choroidal naevus and a freckle?

In the eye, the terms are often used interchangeably. However, a “freckle” tends to refer to a smaller, flat lesion.