Introduction: Who Should Undergo Diagnostics and When

Choroidal melanoma often grows silently inside the eye without causing any noticeable problems at first. Many people discover they have this cancer only when their eye doctor spots something unusual during a regular check-up. Because the tumor develops in the choroid, which is a layer of blood vessels between the white outer wall of the eye and the light-sensitive retina, it can remain hidden from view until it grows larger or begins affecting vision.^[1]

Anyone experiencing changes in their vision should seek medical attention promptly. Symptoms that might suggest something is wrong include seeing flashes of light, noticing floating spots or shapes that drift across your field of view, experiencing blurred vision in one eye, or gradually losing your ability to see to the side. Some people notice a dark spot on the colored part of their eye, or their pupil may change shape. However, many patients have no symptoms at all, which is why regular eye examinations with dilated pupils are so important.^[1][3]

The location of the melanoma within the eye affects how long it takes before symptoms appear. Tumors that start toward the front of the eye, near the colored iris, tend to cause delayed symptoms and may go unnoticed for longer periods. On the other hand, tumors located in the back of the eye, near the central vision area, typically cause vision problems sooner. In rare advanced cases, people may experience severe eye pain, especially if the tumor has caused complications like increased pressure inside the eye.^[1]

If you belong to certain groups, you should be especially vigilant about eye exams. Choroidal melanoma occurs most frequently in people with lighter skin tones, particularly those of European descent, and is more common among individuals with blue or green eyes. The disease typically appears in middle-aged and older adults, with most diagnoses occurring around age 55 to 63. Men are slightly more likely to develop this cancer than women.^[3][12]

Classic Diagnostic Methods

When doctors suspect choroidal melanoma, they use a combination of techniques to confirm the diagnosis and distinguish it from other eye conditions. The process usually begins with a thorough eye examination, but unlike many other cancers, choroidal melanoma can often be diagnosed accurately without removing tissue for a biopsy. In fact, eye cancer specialists who participate in large research studies have shown they can correctly identify choroidal melanoma in more than 96 to 99 percent of cases without needing to cut into the eye.^[2][4]

Comprehensive Eye Examination

The diagnostic journey typically starts with your doctor examining both the outside and inside of your eyes. When looking at the outside, the doctor checks for unusually enlarged blood vessels on the white part of the eye, which might indicate increased metabolic activity from a tumor underneath. These dilated vessels, sometimes called sentinel vessels, can be visible through the clear outer covering of the eye and may feed an actively growing melanoma.^[1]

Looking inside the eye requires special instruments and bright lights. One method, called binocular indirect ophthalmoscopy, uses lenses and a light mounted on the doctor’s head to get a wide view of the retina and the structures beneath it. Another technique, slit-lamp biomicroscopy, employs a microscope with an intense beam of light to examine the eye’s internal structures in fine detail.^[10][24]

Small choroidal melanomas typically appear as dome-shaped, well-defined masses sitting under the layer of pigmented cells at the back of the eye. As tumors grow larger, they can develop more unusual shapes, including bilobular (two-lobed), multilobular (many-lobed), or mushroom-like configurations. Some melanomas grow sideways across the choroid with minimal height, a pattern called diffuse choroidal melanoma, which is harder to diagnose and often causes significant fluid accumulation that lifts the retina away from the back wall of the eye.^[1][14]

The color of choroidal melanomas varies considerably. Some are darkly pigmented, appearing almost black, while others are partially pigmented or even amelanotic, meaning they lack pigment and appear light-colored or flesh-toned. When a tumor is light-colored, doctors can often see its abnormal blood vessel network through the overlying retina. The tissue covering the melanoma usually shows changes such as orange discoloration, areas where cells have died, or small yellowish deposits. Importantly, this orange appearance can occur in both cancerous and non-cancerous growths, so it is not definitive on its own.^[1]

Ultrasonography: A and B Scans

Ultrasound examination is one of the most valuable tools for diagnosing choroidal melanoma. This technology uses high-frequency sound waves to create images of the inside of the eye, similar to how ultrasound is used during pregnancy to see a developing baby. There are two main types of eye ultrasound that doctors use together.^[3][12]

A-scan ultrasonography is particularly useful for tumors that are thicker than 2 to 3 millimeters. This technique measures the internal structure of the tumor by analyzing how sound waves bounce back from different tissues. Choroidal melanoma has a characteristic pattern: the sound wave creates an initial strong spike when it hits the tumor’s front surface, followed by low to medium internal echoes that gradually diminish in strength, and then a significant echo from the back surface. Within the tumor, doctors can often detect fine oscillations in the pattern, which represent pulsing blood vessels feeding the cancer. Taking multiple A-scans and accurately measuring the tumor’s dimensions is crucial when doctors are uncertain about a diagnosis and want to monitor whether a suspicious lesion is growing over time.^[1][14]

B-scan ultrasonography is routinely performed whenever doctors evaluate any mass at the back of the eye. This scan creates a two-dimensional cross-sectional image, allowing doctors to see the tumor’s shape, size, and relationship to surrounding structures. It is especially helpful when other conditions, such as bleeding into the eye or severe retinal detachment, prevent doctors from getting a clear view of the tumor during regular examination. The B-scan can reveal the tumor even when it is hidden beneath these complications.^[1][14]

Specialized Photography and Imaging

Several photographic techniques help doctors document and analyze choroidal melanomas. Fundus photography captures color pictures of the inside surface of the eye, creating a permanent record of the tumor’s appearance that can be compared over time to detect growth. A specialized version called fundus autofluorescence imaging is particularly useful because it can detect orange pigment, called lipofuscin, that accumulates on the tumor’s surface. Lipofuscin is a metabolic waste product that appears when cells die, indicating either that the tumor is destroying overlying tissue or that the tumor itself is degenerating. This finding, along with others, helps doctors determine whether a pigmented growth is likely to be malignant.^[2][10][24]

Fluorescein angiography involves injecting a colored dye into an arm vein and taking rapid photographs as the dye travels through the eye’s blood vessels. This test reveals the tumor’s circulation pattern, which is often abnormal in melanomas. A camera with special filters detects the dye and captures images every few seconds, showing how blood flows through the tumor and whether the tumor is leaking fluid that causes the retina to detach.^[10][24]

Optical coherence tomography (OCT) creates highly detailed, three-dimensional cross-sectional images of the retina and structures beneath it. This technology uses light waves rather than sound waves and can detect even small amounts of fluid beneath the retina that might not be visible with other methods. Fluid accumulation, called subretinal fluid, is created by poorly formed or new blood vessels within the tumor. Cancers need new vessels to support their growth, so the presence of this fluid supports a diagnosis of melanoma rather than a benign growth.^[2]

The MOST Mnemonic

To help eye care specialists systematically evaluate suspicious growths, one doctor developed a memory tool called “MOST.” Each letter stands for a feature that suggests a melanoma diagnosis:^[2]

• M stands for Melanoma itself, the condition being evaluated.
• O represents Orange Pigment Lipofuscin, the metabolic waste visible on autofluorescence imaging.
• S indicates Subretinal Fluid, which ultrasound and OCT can detect.
• T refers to Thickness of the tumor, as measured by ultrasound. It is widely accepted that pigmented tumors thicker than 2.0 millimeters are more likely to be cancerous.

Advanced Imaging When Needed

In certain situations, doctors may order additional imaging studies. Computed tomography (CT) scans can be useful, particularly when doctors suspect the tumor has grown through the wall of the eye into the surrounding bone and tissues of the eye socket. CT scans create detailed cross-sectional images of the eye and orbit using X-rays and computer processing.^[1]

Magnetic resonance imaging (MRI) provides excellent soft tissue detail without using radiation. MRI scans can help characterize the tumor’s internal structure and determine whether it has spread beyond the eye. Some research centers use specialized MRI techniques to study the tumor’s chemical composition.^[1]

Biopsy: When It Might Be Necessary

Unlike most other cancers, choroidal melanoma usually does not require a biopsy, which is the removal of a small tissue sample for examination under a microscope. Because the diagnostic accuracy of experienced eye cancer specialists is so high, and because performing a biopsy requires opening the eye (which carries risks of bleeding, infection, and potentially allowing cancer cells to escape), biopsies are typically avoided.^[2][4]

However, there are situations when a biopsy might be performed. These include cases where the tumor looks atypical and does not fit the classic pattern, when doctors suspect the eye lesion might be a metastasis from cancer elsewhere in the body but no other cancer has been found, or when a patient specifically requests pathological confirmation before proceeding with treatment. More recently, some medical centers have begun routinely performing biopsies primarily to obtain genetic information about the tumor, which can help predict prognosis and guide surveillance for spread to other organs.^[2]

Laboratory Tests

Once choroidal melanoma is diagnosed, doctors typically order blood tests to check liver function. The liver is the most common site where choroidal melanoma spreads when it leaves the eye, so monitoring liver health is an important part of ongoing care. The most sensitive blood tests for detecting liver problems measure levels of specific enzymes and proteins, including alkaline phosphatase, glutamic-oxaloacetic transaminase (also called AST), lactate dehydrogenase (LDH), and gamma-glutamyl transpeptidase. Abnormal levels of these substances might indicate that cancer has spread to the liver, though many other conditions can also affect these test results.^[1][14]

Diagnostics for Clinical Trial Qualification

Clinical trials are research studies that test new treatments or compare different treatment approaches. When patients with choroidal melanoma consider participating in clinical trials, they typically need to undergo specific diagnostic tests to determine if they qualify. These tests serve multiple purposes: they confirm the diagnosis, measure the tumor precisely, assess the cancer’s characteristics, and ensure the patient’s overall health is suitable for the study protocol.

Baseline Tumor Assessment

Most clinical trials require detailed documentation of the tumor’s size and location before treatment begins. This baseline information is essential because researchers need to compare the tumor before and after treatment to determine whether the experimental approach is working. Ultrasound measurements are standard for establishing tumor dimensions, including height, width, and distance from important structures like the optic nerve. The trial protocol may specify minimum or maximum tumor sizes for eligibility, as some treatments are designed specifically for small, medium, or large melanomas.^[1]

Vision and Eye Function Testing

Clinical trials typically measure and document a patient’s vision at the start of the study. This includes testing how well you can see (visual acuity), your ability to see to the sides (peripheral vision or visual field), and sometimes more detailed measurements of retinal function. These baseline measurements allow researchers to track whether treatments affect vision over time, either positively or negatively. Some trials may exclude patients whose vision is already severely impaired, while others specifically study treatments for advanced cases.

Systemic Health Evaluation

Because choroidal melanoma can spread to other parts of the body, particularly the liver, many clinical trials require imaging studies to ensure the cancer has not metastasized before enrollment. This might include CT scans, MRI scans, or PET scans of the chest, abdomen, and pelvis. Blood tests checking liver function are also standard requirements. Some trials focus specifically on treating cancer that has spread, while others only accept patients whose cancer is confined to the eye.

Genetic and Molecular Testing

An increasing number of clinical trials for choroidal melanoma require genetic testing of the tumor. This involves performing a biopsy to obtain tumor cells, which are then analyzed for specific genetic changes or mutations. Some trials test treatments that target particular genetic abnormalities, so only patients whose tumors have those specific changes are eligible. Other trials use genetic information to stratify patients into groups based on their risk of the cancer spreading, allowing researchers to tailor treatments and surveillance strategies accordingly.^[2]

Photography and Imaging Documentation

Clinical trial protocols typically require standardized photography and imaging at specific time points. This might include fundus photography, autofluorescence imaging, OCT scans, and angiography performed at enrollment, during treatment, and at scheduled follow-up visits. These images become part of the research data and allow independent reviewers to assess tumor response to treatment. The frequency and types of imaging depend on what the specific trial is studying.

Quality of Life and Functional Assessments

Some clinical trials include questionnaires or tests that assess how the disease and its treatment affect your daily life. These might measure your ability to perform activities like reading, driving, or recognizing faces. You might also answer questions about symptoms like pain, floaters, or light sensitivity. This information helps researchers understand not just whether a treatment shrinks tumors or preserves vision on paper, but whether it improves patients’ real-world experiences and quality of life.

The specific diagnostic requirements for clinical trial participation vary widely depending on the trial’s design, the treatment being studied, and the research questions being asked. If you are interested in participating in a clinical trial, your medical team will explain exactly which tests you need and help you understand whether you meet the eligibility criteria.