What is an Eye Freckle (Conjunctival Naevus)?

A brown spot noticed in the eye often raises questions such as what is an eye freckle and whether it is harmful. Known medically as a naevus, an eye freckle is a pigmented growth that can appear in different parts of the eye and is benign in the vast majority of cases. It is very similar to the moles on our skin. Eye freckles are made up of cells called melanocytes, which produce melanin, the pigment that gives colour to the eyes, skin and hair. These cells are normally scattered throughout the tissues. In some people, they cluster together in one particular area and form a spot in the shape of a mole. Eye freckles are given different names depending on where they are located:

• Conjunctival naevus: Found on the thin membrane covering the white of the eye and can be noticed in the mirror. It is the most common type of eye freckle.
• Iris naevus: Appears as a dark dot or spot on the iris, the coloured part of the eye.
• Choroidal naevus: Located inside the eye, in the vascular layer beneath the retina. It cannot be seen from the outside and is usually discovered by chance during a fundus examination.

Moles can also appear on the skin of the eyelids. Most eye freckles cause no problems at all; however, because they can rarely change, it is important for them to be assessed and monitored by an ophthalmologist.

Causes of an Eye Freckle

Although the exact causes of an eye freckle are not fully known, it is accepted that it forms when melanocytes cluster together in one area. A significant proportion of eye freckles are present from birth or become more noticeable during childhood and adolescence. Factors thought to play a role in the formation of an eye freckle include:

• Genetic predisposition: Having a large number of moles, either yourself or in your family, may be linked to a higher likelihood of an eye freckle.
• Sunlight (UV) exposure: Prolonged, unprotected exposure to sunlight is thought to play a role in pigmented growths.
• Hormonal periods: During periods such as puberty and pregnancy, existing moles may darken or become more noticeable.

An eye freckle is not an infection. Germs such as viruses, bacteria or fungi do not cause eye freckles, and an eye freckle is not contagious.

Symptoms of an Eye Freckle

In most cases there are no symptoms of an eye freckle. Eye freckles do not usually cause complaints such as pain, itching, redness or loss of vision. Conjunctival and iris naevi are mostly noticed by the person in the mirror or spotted by those around them, whereas choroidal naevi are found by chance during a routine eye examination. Conjunctival naevi may look brown, light brown or sometimes almost colourless, and may contain small cyst-like structures. If there are complaints such as redness, watering or burning in the eye, these are usually caused not by the naevus but by another accompanying eye problem, which should be assessed separately.

Why Is Monitoring an Eye Freckle Important?

The vast majority of eye freckles remain benign for life. Very rarely, however, an eye freckle can turn into a malignant tumour called ocular melanoma. For this reason, people with an eye freckle are advised not to miss their regular eye check-ups. The following changes are among the warning signs that need attention:

• The freckle growing larger or becoming raised
• Darkening, lightening or uneven distribution of its colour
• A change in its shape or borders
• New blood vessels appearing on or around the freckle
• Blurring or other changes in vision
• Seeing flashes of light or floaters in the eye

So that these changes can be spotted early, the ophthalmologist records the appearance of the freckle at the first examination with photographs. At later check-ups, new images are compared with these records. The interval between check-ups is set by the doctor according to the location and features of the freckle.

Diagnosis of an Eye Freckle

Diagnosis of an eye freckle is made through an examination by an ophthalmologist. Conjunctival and iris naevi at the front of the eye are examined in detail with a slit lamp, also known as a biomicroscope. To see choroidal naevi inside the eye, the pupil is dilated with drops and a fundus examination is carried out. The following methods may be used during the examination and follow-up:

• Photography: Anterior segment or fundus photographs allow the size and colour of the freckle to be compared over time.
• Optical coherence tomography (OCT): Particularly for choroidal naevi, it shows the retinal layer over the freckle and whether there is any fluid build-up.
• Eye ultrasound: Can be used to measure and monitor the thickness of choroidal naevi.

If a suspicious finding is detected during the examination, further investigation may be needed. For freckles that are removed surgically, a definitive diagnosis is made by pathological examination of the tissue. For more information on the tests used in an eye examination, you can read our article Which Tests Are Done in an Eye Examination?

Eye Freckle Treatment

In most cases, eye freckle treatment is not needed. For eye freckles that show no change and look benign, the recommended approach is examination at regular intervals and photographic monitoring. In some cases, conjunctival naevi may be removed surgically:

• A suspicious finding such as growth or a change in colour or shape during follow-up
• The freckle bothering the person for cosmetic reasons
• The freckle causing irritation or discomfort

In this procedure, the freckle is removed from the conjunctiva together with a small margin of the surrounding healthy tissue, and the removed tissue is sent for pathological examination. The scope of the procedure and the appropriate method are decided by the ophthalmologist according to the location and size of the freckle. Because iris and choroidal naevi sit within the inner structures of the eye, they are not usually removed; instead they are monitored with examinations, photographs, OCT and, where necessary, ultrasound. If a malignant change is suspected during follow-up, the person is referred for further assessment and treatment. As an eye freckle is not an infection, eye drops, antibiotics or other medicines do not make it disappear. If redness or irritation accompanies the freckle, the doctor may recommend separate treatment for these complaints.

When Should You See an Ophthalmologist?

If you notice a freckle or spot in your eye that you had not seen before, it is advisable to have it examined by an ophthalmologist. If you notice growth, a change in colour or shape, or new blood vessels on a known eye freckle, or if new complaints such as blurred vision, flashes of light or floaters begin, it is best to see an ophthalmologist without waiting for your check-up appointment. Wearing sunglasses with UV protection in sunny conditions helps to protect eye health. It is also important for people with an eye freckle to keep attending check-ups at the intervals recommended by their doctor.