A retinal nevus is a small, flat, pigmented spot found inside the eye during a routine exam, essentially a freckle on the tissue lining the back of the eye. Most are located in the choroid, the blood vessel-rich layer beneath the retina, which is why eye doctors usually call them choroidal nevi. They are common, turning up in roughly two to seven percent of adults depending on the population studied, and the vast majority never cause symptoms or require treatment. The reason they matter at all is that a tiny fraction can transform into uveal melanoma, a rare but serious eye cancer, so understanding what separates a harmless nevus from a worrisome one is genuinely useful.
How Common Are They, and Who Gets Them
Population studies put the prevalence of choroidal nevi somewhere between about two and seven percent of adults, with the exact number depending on the racial makeup and age range of the group studied. A large analysis using U.S. national health survey data found an overall prevalence of about 4.7 percent in adults over 40, with a clear trend toward higher rates in older people: roughly three percent in those aged 50 to 59, rising to about 7.5 percent in people 80 and older.1PubMed. Choroidal Nevus in the United States Adult Population: Racial Disparities and Associated Factors in the National Health and Nutrition Examination Survey An Australian study of a predominantly white population found a rate of 6.5 percent, with a borderline trend suggesting nevi were slightly more common in younger participants.2JAMA Ophthalmology. Choroidal Nevi in a White Population: The Blue Mountains Eye Study
Race is one of the strongest predictors. In the U.S. data, whites had a prevalence of about 5.6 percent, compared with 2.7 percent in Hispanic Americans, and just 0.6 percent in Black Americans. After adjusting for age, the odds of having a choroidal nevus were roughly ten times higher in whites than in Blacks.3PubMed. Choroidal Nevus in the United States Adult Population: Racial Disparities and Associated Factors in the National Health and Nutrition Examination Survey A separate multi-ethnic study confirmed a similar pattern, reporting overall prevalence of 2.1 percent across all groups, with whites at 4.1 percent, Blacks at 0.7 percent, Hispanics at 1.2 percent, and Chinese Americans at 0.4 percent.4PubMed Central. Prevalence and characteristics of choroidal nevi: the multi-ethnic study of atherosclerosis The disparity mirrors what happens with skin freckles and moles, which are also far more common in lighter-skinned individuals, likely because lighter eyes and lighter choroids make it easier both for melanocytic spots to develop and for clinicians to detect them photographically.
What a Retinal Nevus Actually Is
A choroidal nevus is a cluster of melanocytes, the pigment-producing cells that also create moles on your skin. In the eye, these melanocytes normally live in the choroid and the uveal tract. When a small group of them proliferates and settles into a flat or slightly raised patch, it forms a nevus. Most nevi are darkly pigmented, though a small percentage appear lighter or even amelanotic, meaning they lack obvious pigment. On clinical exam they are typically flat, a few millimeters across, and located behind the equator of the eye, in the area you’d see when looking through a dilated pupil.
Research into the molecular drivers of these lesions has found that the vast majority harbor a mutation in one of two closely related genes, GNAQ or GNA11. In one study, 15 of 16 choroidal nevi carried one of these mutations.5PubMed Central. GNAQ and GNA11 mutations and downstream YAP activation in choroidal nevi These same mutations are also found in uveal melanoma, which raises the question of why most nevi stay benign while a handful progress. The answer appears to involve a downstream signaling molecule called YAP. In nevi, YAP activity is patchy and heterogeneous, with mutant cells making up a relatively small fraction of the total. The researchers suggested that GNAQ/GNA11-mutant cells may stimulate neighboring normal melanocytes to proliferate through YAP signaling, creating a mixed population that stays controlled.6British Journal of Cancer. GNAQ and GNA11 mutations and downstream YAP activation in choroidal nevi For a nevus to become cancerous, additional genetic hits beyond these initial mutations are apparently required.
Do They Cause Symptoms
The short answer for most people is no. The majority of choroidal nevi are discovered incidentally during a dilated eye exam, and the patient has never noticed a thing. Vision problems are uncommon even with relatively large nevi. In a study of 322 “giant” choroidal nevi, which are substantially bigger than typical ones, only about two percent of patients had nevus-related vision loss at the time of diagnosis, and about four percent had vision loss by the end of follow-up (a median of roughly three and a half years later).7PubMed. Giant choroidal nevus clinical features and natural course in 322 cases So even among the largest nevi, the odds of meaningful visual impact are low.
When a nevus does affect vision, the culprit is usually its location or a secondary complication rather than the nevus itself. If the lesion sits on or very near the fovea, the pinpoint center of sharp vision, it can distort the overlying retinal layers enough to blur your sight. Subretinal fluid, a pocket of liquid that seeps under the retina above the nevus, is another common cause of decreased vision. In the giant-nevus study, both proximity to the fovea and the presence of subretinal fluid were the strongest predictors of visual loss.8PubMed. Giant choroidal nevus clinical features and natural course in 322 cases A rarer complication is choroidal neovascularization, where abnormal new blood vessels grow from the choroid through the nevus and leak fluid or blood under the retina. This can be treated in much the same way as the wet form of age-related macular degeneration: with injections of anti-VEGF drugs.9PubMed. Choriocapillary vascular density changes in choroidal neovascularization associated with choroidal nevus after anti-VEGF injections
The Risk of Turning into Melanoma
This is the question that drives most of the clinical attention nevi receive, and the honest answer is that the risk for any individual nevus is very low. The challenge is that uveal melanoma, while rare overall, is the most common primary eye cancer in adults, and it tends to start as a small pigmented lesion that initially resembles a nevus. Distinguishing a large stable nevus from a small early melanoma can be genuinely difficult, even for experienced specialists.10PubMed Central. What’s in a Name? Large Choroidal Nevus, Small Choroidal Melanoma, or Indeterminate Melanocytic Tumor
The landmark study on this followed 2,514 consecutive choroidal nevi and tracked which ones eventually grew into melanoma. The researchers identified several features that predict transformation, and those features have been organized into a mnemonic that eye doctors widely use. The factors are thickness greater than about two millimeters on ultrasound, the presence of subretinal fluid, symptoms like blurred vision or flashes, orange pigment on the surface of the lesion, proximity of the nevus margin to the optic disc, internal acoustic hollowness on ultrasound, and the absence of a surrounding halo.11JAMA Ophthalmology. Choroidal Nevus Transformation Into Melanoma: Analysis of 2514 Consecutive Cases Each of these roughly doubled or tripled the hazard of transformation on its own, with absent halo carrying the highest individual risk.
A nevus with none of these risk factors has only a tiny chance of becoming melanoma. The more factors present, the higher the suspicion. In clinical practice, a nevus scoring zero on the standard risk-factor checklist can be monitored with relatively infrequent visits, while one with several flags warrants closer surveillance or even early treatment. A cost-utility analysis confirmed this logic, finding that targeting monitoring resources at higher-risk nevi and spacing out visits for low-risk ones makes both clinical and economic sense.12PubMed Central. Follow the nevus: the cost-utility of monitoring for growth of choroidal nevi
How Clinicians Evaluate and Monitor a Nevus
If your eye doctor spots a choroidal nevus, the first step is careful documentation. A color photograph through a dilated pupil establishes a baseline for comparison. Ultrasound can measure the thickness and internal reflectivity of the lesion, both of which matter for risk stratification. But the imaging tool that has changed nevus management most in recent years is optical coherence tomography, or OCT, a non-invasive scan that produces cross-sectional images of the retina and choroid in extraordinary detail.
Enhanced-depth OCT reveals features invisible to the naked eye. In a study of 104 nevi, the most common OCT findings included shadowing deep to the nevus (seen in over 90 percent of cases), thinning of the tiny blood vessel layer overlying the nevus, and changes in the retinal pigment epithelium and photoreceptor layers above it.13PubMed. Enhanced depth imaging optical coherence tomography of choroidal nevus in 104 cases A separate study classified flat nevi into five distinct OCT patterns based on how the nevus sat within the choroid, ranging from not visible at all on OCT to clearly elevated above the surrounding tissue.14Ophthalmology Retina. Enhanced Depth Imaging OCT of Ultrasonographically Flat Choroidal Nevi Demonstrates 5 Distinct Patterns
Another technique, autofluorescence imaging, detects a substance called lipofuscin in the retinal pigment epithelium. A bright autofluorescence signal over a lesion suggests an overabundance of lipofuscin, which is associated with active metabolic disturbance and is more common in small melanomas. A dark signal, by contrast, reflects chronic damage from a stable nevus. Combining ultrasound, OCT, autofluorescence, and standard photography into a multimodal approach allows clinicians to objectively assess the risk factors for transformation.15Translational Vision Science & Technology. White Paper on Ophthalmic Imaging for Choroidal Nevus Identification and Transformation into Melanoma
Scoring Systems for Risk
To standardize how risk is communicated, researchers have developed scoring systems. Two widely used ones are the TFSOM-DIM score and the MOLES score. Both assign points based on the clinical and imaging features of the lesion. In a study comparing the two systems in 211 patients with nevi, half of nevi scored zero on the TFSOM-DIM scale, meaning none of the major risk factors were present. About a third scored one, and the remaining 18 percent scored two or higher. The most common risk feature among nevi was simply having a diameter of five millimeters or more, present in about a third of cases, followed by symptomatic vision loss in 15 percent and orange pigment in 10 percent.16Scientific Reports. Performance of the MOLES and TFSOM-DIM scores in classifying choroidal nevi and melanoma The two scoring systems correlated with each other well, and higher scores on either consistently tracked with a greater likelihood that the lesion was or would become melanoma.
Scores like these help manage a common source of patient anxiety. Being told you have an “eye freckle” that needs monitoring can sound alarming, but knowing that a score of zero corresponds to near-zero risk of transformation can provide real reassurance. For clinicians, the scores also guide follow-up intervals: a zero-scoring nevus might be re-imaged annually, while a lesion scoring three or higher would likely be seen every few months or referred for treatment evaluation.
Choroidal Nevi in Children
Most research on retinal nevi focuses on adults, but they do occur in children, and the pattern is different in some respects. A study of more than 5,500 children found that prevalence increased with age, from about 0.5 percent in children under six to roughly 1.8 percent by age 18. All nevi were in one eye only, virtually all were pigmented, and they were uniformly small, with an average diameter of about 1.6 millimeters. None of the nevi in this study showed secondary changes like subretinal fluid or orange pigment, and no malignant transformation occurred during follow-up.17PubMed. Choroidal nevi in children: prevalence, age of onset, and progression
A second pediatric study with longer follow-up painted a broadly similar picture but with a cautionary note. In 79 children with choroidal nevi followed for a median of about 44 months, two nevi (about 2.4 percent) ultimately transformed into melanoma, both discovered at around 50 months of follow-up. The nevi in this cohort were somewhat larger on average, at about 3.4 millimeters in diameter, and a small percentage had subretinal fluid at presentation.18Investigative Ophthalmology & Visual Science. Clinical Features and Multimodal Imaging Characteristics of Choroidal Nevi in Pediatric Patients Transformation in children is extremely rare, but these findings confirm that it is not zero, especially for larger or atypical lesions. The general approach is the same as for adults: document the lesion and follow it over time.
The Link to Skin Moles and Dysplastic Nevus Syndrome
A question people often have after learning about a choroidal nevus is whether it has anything to do with the moles on their skin. The two share a cellular origin in melanocytes, and some evidence supports a real connection. A study of patients with dysplastic nevus syndrome, a condition characterized by a high number of atypical skin moles, found that these patients were significantly more likely to have nevi inside the eye as well. Roughly 14 percent of those with the syndrome had choroidal nevi, compared with about five percent of controls. The rates of iris nevi and conjunctival nevi were also elevated in the syndrome group.19Dermatologic Clinics. Ocular Findings in Patients with Dysplastic Nevus Syndrome An Update
This does not mean that everyone with a choroidal nevus has a mole disorder. Having a single eye freckle is extremely common and usually meaningless. But if you have been diagnosed with dysplastic nevus syndrome or have a strong family history of atypical moles and melanoma, mentioning it to your eye doctor is worthwhile, since the overall melanoma surveillance picture may include your eyes as well as your skin.
When a Nevus Sits on the Optic Disc
Most choroidal nevi are located in the posterior fundus, away from the optic nerve head. But a related lesion called a melanocytoma can arise directly on the optic disc. These are deeply pigmented tumors made of plump melanocytes, and they are technically a variant of melanocytic nevus. Although they were long thought to be entirely stationary, it is now recognized that about 10 to 15 percent show minor enlargement over time. More important, about one to two percent undergo malignant transformation into melanoma.20PubMed Central. Melanocytoma of the optic disk: A review A melanocytoma can also cause visual loss on its own by compressing the optic nerve fibers beneath it, or through vascular complications. These lesions require their own monitoring schedule, typically with serial photography and visual field testing.
Artificial Intelligence in Nevus Screening
One of the more promising recent developments is the use of deep learning algorithms to distinguish choroidal nevi from small melanomas on standard fundus photographs. A validated algorithm achieved strong performance in differentiating the two, and in head-to-head comparisons it outperformed ophthalmologists who were using the established risk-factor scoring systems alone.21Ophthalmology Science. Development and Validation of a Deep Learning Algorithm for Differentiation of Choroidal Nevi from Small Melanoma in Fundus Photographs The practical appeal is straightforward: fundus photographs are cheap and widely available, and an AI second opinion could help primary eye-care providers decide which patients need urgent referral to a specialist and which can safely be followed at longer intervals. The technology is still in the validation phase and not yet a standard clinical tool, but it points toward a future where the anxiety of an ambiguous nevus could be resolved more quickly and reliably.
What Monitoring Actually Looks Like for Patients
If you have been told you have a choroidal nevus, the typical plan involves periodic dilated eye exams with photographic documentation so that any changes can be detected by comparison over time. For a small, flat, featureless nevus with no risk factors, many retinal specialists recommend an exam every 12 months. If the lesion has one or two concerning features, you might be seen every four to six months. A nevus with several risk factors, or one that has already shown documented growth, would prompt discussion about early intervention, which usually means either focal radiation or laser treatment.
Between visits, there is very little you can do to change the nevus. No dietary supplement, sun protection regimen, or lifestyle modification is known to prevent transformation. The value of monitoring is entirely in early detection: if a nevus does begin to grow, catching it when it is still a small melanoma gives you far better treatment outcomes than catching it later. Most indeterminate pigmented lesions can be followed safely with serial observation and standard imaging.22PubMed. Natural history of indeterminate pigmented choroidal tumors That is reassuring, because it means the standard approach of watchful waiting is backed by decades of clinical data, not just medical tradition.
When Treatment Becomes Necessary
True treatment of a choroidal nevus itself is almost never performed. The lesion is benign, and removing it would cause more damage to the eye than leaving it in place. Intervention enters the picture in two scenarios: transformation into melanoma, and secondary complications like choroidal neovascularization.
If a nevus transforms, treatment options include plaque brachytherapy, in which a small radioactive disc is temporarily sutured to the outside of the eye over the tumor, proton beam radiation, or, in advanced cases, removal of the eye. The choice depends on the size and location of the tumor. For the separate problem of neovascularization growing from a nevus, anti-VEGF injections into the eye can shut down the abnormal blood vessels and stabilize vision. One case series demonstrated regression of the neovascular activity after just two monthly injections.23PubMed. Choriocapillary vascular density changes in choroidal neovascularization associated with choroidal nevus after anti-VEGF injections Photodynamic therapy, a laser-activated drug treatment, has also been used for subfoveal neovascularization growing from a nevus.24PubMed. Photodynamic therapy for choroidal neovascularization secondary to choroidal nevus These complications are uncommon, but they are treatable, which is another reason routine monitoring matters.