When a child is brought to the pediatrician or family doctor with signs or symptoms that could indicate retinoblastoma, the young patient is usually referred to a pediatric ophthalmologist or to an ocular oncologist to confirm the diagnosis.
The ocular oncology team at UT Southwestern uses the most advanced and accurate equipment available to make a diagnosis of retinoblastoma.
Diagnosing Retinoblastoma
After performing a thorough medical history, the ocular oncologist will perform an examination while the child is under anesthesia and use a variety of equipment to make the diagnosis of retinoblastoma. Biopsies are rarely performed to diagnose this disease, due to the concern of spreading cancer cells.
To diagnose retinoblastoma, we may use:
- Retinal examination: Using an indirect ophthalmoscope, the ocular oncologist will examine the entire retina while the patient’s eyes are dilated. This is a very important part of the diagnostic work-up, as an experienced ocular oncologist can diagnose retinoblastoma simply by looking at the tumor.
- Retinal photography: UT Southwestern and Children’s Medical Center use state-of-the-art retinal fundus cameras to document and measure all retinoblastomas in each eye and monitor their size over time after treatment is administered.
- Ultrasonography: This is a test that uses sound waves to produce detailed images of the inside of the eye and eye socket. This test is critical for measuring the size of tumors and detecting retinal detachment, calcium deposits, tumor seeding, and other features that are important in diagnosing and staging retinoblastoma.
- Optical coherence tomography (OCT): This test uses lightwaves to create a high-resolution image of the retina, which can be very useful in detecting small retinoblastomas.
- Fluorescein angiography: This test involves injecting a nonradioactive fluorescent dye into a vein in the arm or hand, then photographing the retina as the dye passes through the retinal blood vessels to detect changes in their structure or function. It can help to distinguish retinoblastoma from other abnormalities in the eye and assess response to therapy.
- Electroretinogram (ERG): This test is rarely needed but in select patients can be used to assess the health and visual potential of the retina by measuring electrical responses of the light-sensitive retinal cells.
- Magnetic resonance imaging (MRI): This is a test performed in the radiology unit to evaluate the eye, eye sockets, and brain. MRI is very important as an initial baseline examination; it is used periodically thereafter to determine the extent of retinoblastoma and assess response to therapy.
- Genetic testing: Depending on the family history and other circumstances, genetic testing may be recommended to assess for a germline mutation in the RB1 gene to determine if the retinoblastoma is hereditary or non-hereditary.
Stages of Retinoblastoma
The International Intraocular Retinoblastoma Classification (IIRC) is the staging system that most ocular oncologists now use. It divides retinoblastomas into five groups based on the extent of the cancer within the eye and on the chances the eye can be saved using current chemotherapy.
- Group A: Small tumors, no more than 3 millimeters across, confined to the retina and not near important structures of the eye.
- Group B: Tumors that are still confined to the retina and larger than 3 mm or close to important structures.
- Group C: Tumors with localized spread of tumor clumps or “seeds” into the jellylike vitreous gel or under the retina.
- Group D: Tumors with more extensive seeding into the vitreous or under the retina. The retina may have become detached from the back of the eye.
- Group E: Tumors that are very large, extend to the front of the eye, cause bleeding or glaucoma (high pressure inside the eye), or have high-risk features that indicate a risk of spread outside of the eye.
After retinoblastoma has been diagnosed and staged, UT Southwestern ocular oncologists work with the family to customize a treatment plan for each patient.
