Eye cancer, such as uveal melanoma or retinoblastoma, is a rare but serious disease. Diagnosis involves specialized examinations and technological studies performed by ophthalmologists and ocular oncologists. This multi-step approach detects a suspicious lesion, confirms its cancerous nature, and determines the extent of the disease. The findings directly influence the subsequent treatment strategy.
Initial Eye Examination
The diagnostic process begins with a thorough physical assessment performed by an eye specialist, often before a patient experiences any noticeable symptoms. This initial evaluation includes a visual acuity test to measure the sharpness of vision and an examination of eye movement. The doctor also inspects the outside of the eye for visible signs, such as enlarged blood vessels, which may indicate an internal tumor.
Pupil dilation is performed using eye drops, which temporarily widens the pupil and allows a clearer view into the eye’s interior structures. The specialist uses a binocular indirect ophthalmoscope, a head-worn instrument providing a wide, stereoscopic view of the retina and the back of the eye. A slit lamp, a microscope paired with a bright light, is also used for high-magnification views of both anterior and posterior structures. This detailed inspection often detects asymptomatic lesions, like small choroidal melanomas.
Advanced Imaging Studies
Once a suspicious lesion is identified, advanced imaging techniques confirm the tumor’s presence, measure its dimensions, and analyze its internal characteristics. Ocular ultrasound is a frequently used non-invasive tool, relying on high-frequency sound waves to create images of the eye’s internal structures. This is particularly useful when the view into the eye is obscured by conditions like cataracts or vitreous hemorrhage.
The B-scan (brightness scan) provides a two-dimensional, cross-sectional image, allowing the doctor to determine the precise shape and location of the mass. The A-scan (amplitude scan) provides a one-dimensional measurement of the tumor’s thickness along a specific line. The A-scan also helps assess the tumor’s internal consistency by measuring its echogenicity, which is how strongly the sound waves reflect off the tissue.
Additional imaging studies evaluate the tumor’s involvement with surrounding tissues and its blood supply. Magnetic Resonance Imaging (MRI) provides detailed soft tissue images, visualizing the extent of the tumor within the orbit and checking for spread along the optic nerve. Fluorescein angiography involves injecting a harmless dye into the bloodstream and taking photographs as it circulates, highlighting abnormal blood vessel patterns associated with cancerous growth. Computed Tomography (CT) scans may also be used to visualize the bony structures of the eye socket and surrounding areas.
Biopsy Procedures and Pathology
While imaging can suggest cancer, a tissue sample is often required for a definitive diagnosis and prognosis. Eye biopsies are typically avoided unless necessary for treatment planning, due to the risk of complications, including potential vision loss or tumor spread. When performed, the procedure is often a fine-needle aspiration biopsy (FNAB), which uses a thin needle to collect cells from the tumor.
The collected sample is analyzed by a pathologist, who determines the exact type of cancer and its grade. For uveal melanoma, pathologists classify the cells as spindle, epithelioid, or mixed. Tumors with more epithelioid cells are associated with a less favorable prognosis compared to those composed primarily of spindle cells. Genetic analysis of the tissue sample can also be performed, looking for specific chromosomal changes like monosomy 3, or using gene-expression profiling to predict the likelihood of the cancer spreading.
Assessing Tumor Extent (Staging)
The final diagnostic step involves determining the tumor’s extent, a process known as staging, which guides the treatment plan. Staging uses the tumor’s size (T), the involvement of nearby lymph nodes (N), and the presence of distant metastasis (M) to classify the disease. Since ocular cancers frequently metastasize to the liver, this organ is a primary focus during staging.
Doctors use additional body scans to check for cancer spread outside the eye. This often includes an abdominal ultrasound to examine the liver for secondary tumors, along with chest X-rays or CT scans to check the lungs. Positron Emission Tomography (PET) scans may be utilized, where a radioactive tracer is injected to detect metabolically active cancer cells throughout the body.