- Published on
Ophthalmology – Choroidal Nevus
Choroidal nevus is the most common intraocular tumor and represents a benign melanocytic lesion arising within the uveal tract, most commonly in the choroid. It typically appears as a pigmented (brown in about 80% of cases) or less commonly nonpigmented lesion. Most nevi are small, measuring approximately 2 mm in diameter and 1.5 mm in thickness, and may be associated with overlying retinal pigment epithelium (RPE) changes such as drusen, hyperplasia, or atrophy. Although benign, careful evaluation is essential to differentiate it from choroidal melanoma.
Epidemiologically, choroidal nevus is far more common in Caucasians, particularly those with blue eyes. The overall prevalence is estimated to be around 7% in Caucasian adults, with increasing detection rates with age. Although believed to be present from birth, most nevi are identified later in life when pigmentation develops or during routine dilated fundus examinations. It affects both genders equally, though some studies suggest a slight female predominance.
Risk factors primarily include fair skin and light-colored eyes, reflecting a predisposition in individuals with less ocular pigmentation. There is no known hereditary pattern or genetic predisposition, and no established method of prevention. The exact pathophysiology and etiology remain unknown, although it is considered a benign proliferation of melanocytes within the choroid.
Most patients with a choroidal nevus are asymptomatic, with approximately 84% having no visual complaints. A minority may experience decreased vision, flashes, floaters, or visual field defects depending on the lesion’s location, particularly if it involves the macula. On examination, the lesion appears as a flat or minimally elevated pigmented area, commonly located outside the fovea.
Diagnosis is primarily clinical, supported by multimodal imaging. Fundus photography helps document size and location, while ultrasonography assesses thickness. Optical coherence tomography (OCT) is useful for detecting subretinal fluid or retinal changes overlying the nevus. Fluorescein and indocyanine green angiography can evaluate vascular characteristics, and autofluorescence imaging helps assess RPE health. These tools are also critical for monitoring stability over time.
A key aspect of management is distinguishing benign nevi from lesions at risk of malignant transformation. Risk factors suggesting possible progression to melanoma can be remembered with the mnemonic “To Find Small Ocular Melanoma Using Helpful Hints Daily,” which includes thickness greater than 2 mm, subretinal fluid, symptoms, orange pigment, proximity to the optic disc, ultrasound hollowness, absence of halo, and absence of drusen. Lesions with multiple risk factors warrant closer observation or referral.
There is no medical treatment for choroidal nevus. Management typically consists of observation with periodic follow-up every 3–6 months initially, then biannually if stable. Imaging is repeated to detect any growth or development of suspicious features. Intervention is considered only if there is documented growth or complications such as subretinal fluid affecting vision, which may prompt treatments similar to those used for melanoma.
The prognosis is excellent for stable lesions without growth. Visual outcome depends largely on location; extrafoveal lesions usually preserve vision, whereas subfoveal nevi may lead to visual decline. The main complication is rare transformation into choroidal melanoma, as well as potential vision loss if the lesion affects the macula.
0 Comments
