Benign Choroidal Nevus: The Eye Freckles

Introduction:

The choroidal nevus or nevi (plural form) gets its name from its site called the choroid. This refers to a tissue layer enriched by blood vessels between the sclera (white portion of the eye) and retina (the innermost and sensory membrane layer of the eye present at the back region). Moreover, choroids possess higher levels of blood flow in the body. The choroid is known for many significant functions, including oxygen and nutrition supply for the outer portion of the retina. A choroidal nevus is a common type of growth characterized by a spot on the choroid. This condition is sometimes referred to as eye freckles.

A choroidal nevus is a relatively common eye condition occurring in about 3.4 percent of the world's population. This condition's prevalence among Americans over 40 years is about 4.7 percent. The clinical reports signify that the frequency of choroidal Nevi is higher in whites than in blacks, Chinese, and Hispanics. Hence, age and race play a significant role in the incidence of choroidal nevi.

What Is Choroidal Nevus?

The choroidal nevus is a benign neoplasm of the choroid. The characteristic feature of this condition is grayish-brown pigmented lesions associated with blurred margins. Choroidal nevus can be of varied colors, such as brown, yellow, gray, or multicolored.

The lesion of choroidal nevi is mostly the same size as the optic disc (optic nerve head of the nerve assessing the eye) and appears to be an oval or round shape. So, choroidal nevus is typically a benign tumor or cancerous condition of the choroid layer made up of melanocytes, whereas melanocytes refer to melanin pigment-producing cells.

What Causes Benign Choroidal Nevus?

The exact cause of the choroidal nexus is still undetermined. However specific findings say that an increased melanin production due to DNA photodamage to melanocytes could lead to the deposition of excess melanin in the choroidal tissues. The causative factors include exposure to ultraviolet (UV) B radiation and other risk determinants.

What Are the Signs and Symptoms Associated With Choroidal Nevus?

The condition benign choroidal nevus usually shows no symptoms. So, people with this condition encounter symptoms in rare instances. Nevertheless, individuals can become symptomatic when fluid leakage occurs, which is normally associated with neovascularization (abnormal growth of blood vessels). The following symptoms can result from such changes in choroidal nevus.

• Localized retinal detachment (Retina is lifted or pulled away from its actual position).

• Flashing lights.

• Loss of vision- central and peripheral vision loss.

• Retinal degeneration.

• Cystoid retinal edema (painless edema affecting the retina).

• Blurred vision.

• Bleeding.

How Is Benign Choroidal Nevus Diagnosed?

Choroidal nevus can only be identified after its progression to a symptomatic form. In contrast, it can also be detected during the regular eye examination. Health care providers, particularly ophthalmologists, identify choroidal nevi by its specified appearance. The thickness will likely be approximately two millimeters, with the color showing brown to slate gray. The edges of the lesion may look blurry with its blending into the retina. Moreover, one person can have more than one choroidal nevus or nevi in both eyes. The diagnostic testing of choroidal nevus includes the following.

• Ultrasound: This utilizes high-frequency ultrasound waves to detect and produce comprehensive images of the eye and orbit.

• Optical Coherence Tomography: This non-invasive diagnosis provides an inner and cross-sectional view of the retina. This allows healthcare providers to take direct photographs of rendered eye images.

• Fluorescein Angiography: Fluorescein angiography is a diagnostic technique used to examine the circulation of the choroid and retina. This utilizes a specialized camera and fluorescent dye for imaging.

• Optomap: This approach is considered the most common diagnostic method for assessing choroidal nevus from malignant melanoma (a cancerous choroidal nevus). This takes the image of the lesion using two distinct lasers (green and red). So a green laser makes the nevus invisible while melanoma is visible. Hence, this approach can help distinguish both conditions.

How Is Benign Choroidal Nevus Treated?

Treatment is not required in most cases of choroidal nevus. This is because choroidal nevi typically do not show any adverse effects. Additionally, no safer treatments are available to remove the choroidal nevus from the eye. Most cases can be effectively managed and assessed by OCT. The neovascularization associated with choroidal nevus can be addressed and treated using anti-vascular endothelial growth factor (anti-VEGF) agents through intravenous injection. These drugs aid in activating the vascular endothelial growth factors, reducing swelling and neovascularization. But if the choroidal nevus has been transformed into melanoma, it will be treated with conventional treatments like surgery, radiation therapy, and chemotherapy.

Is Choroidal Nevus a Cancerous Condition?

Most cases of choroidal nevi are benign and result in no significant damage. It is more similar to the moles and freckles on the skin. But, in rare cases, this condition can grow into malignant melanoma. So, a benign choroidal nevus can develop into a cancerous condition over time. The cancerous form of choroidal nevus is called choroidal melanoma. Choroidal melanoma is considered a dangerous ophthalmic malignant condition. This melanoma is probably sight-threatening and fatal. The annual and estimated rate of malignant transformation of choroidal nevus to chordal melanoma is about one in 8,845.

Therefore, the only risk of cordial nevus is that it might potentially transform into malignant choroidal melanoma. Melanoma concerning the eye is known to be the most common eye cancer.

How Choroidal Nevus Transforms Into Melanoma?

Choroidal nevus and choroidal melanoma are two distinct conditions. Generally, the nevi occurs more commonly compared to melanoma. The research findings say that about one in 9000 cases of nevi can transform into melanoma. The following signs show a higher risk of developing melanoma.

• Tumor with a greater thickness of about two millimeters (Tumor size two times or bigger than the size of optic nerve head).

• Symptoms like flashing lights, reduced vision, vision impairment, and orange pigmentation.

• The distance between the optic disk and the tumor margin is less than three millimeters.

• Subretinal fluid or leakage of the fluid.

• Ultrasonography hollowness (hollowness of nevi on ultrasonography).

• Lack of absence of halo.

Conclusion:

A benign choroidal nevus is not a profound concern unless it remains benign with no symptoms or adverse effects. However, eye evaluation and checkups are essential annually by ophthalmologists. The American Academy of Ophthalmology suggests adult people aged 49 years and above undergo a comprehensive eye examination.