The inside of the eye (intraocular portion) can be affected by tumors (abnormal growth of tissue) just like other parts of the body. In general, intraocular tumors can be divided into two categories: Primary (tumors that start from the eye tissue itself) and Secondary (tumors that spread to the eye from another organ).
Secondary tumors are more common than primary tumors in the eye, but are generally found in people with a known diagnosis of metastatic malignancy. Cancer metastasis that end up in the eye are most commonly from breast cancer in women and lung cancer in men. In children, the most common type of metastatic cancer to the eye is from neuroblastoma tumor. Metastasis to the eye can occur from other organs such as prostate and bone marrow (leukemia).
The layer underneath the retina, called the choroid contains the same cell line that gives skin pigment, called melanocytes. Just as you can get a collection of melanocytes on the skin to cause a freckle, you can also get the same phenomenon, called a choroidal nevus to form in the back of the eye (see picture below).
Choroidal nevus is the most common tumor seen in the back of the eye and normally develops during puberty and early adulthood. They are found in 2-10% of the population and are most common in Caucasians and least common in African Americans.
Occasionally, these nevi can transform into melanoma, just like can occur with a mole on your skin. This tumor, called a choroidal melanoma is the most common primary malignancy inside the eye. A main risk factor for having ocular melanoma is having lighter skin, but unlike skin cancer, tumor risk is not associated with sun exposure. It is for this reason that nevi require monitoring for growth. In general, the nevi with the lowest risk for transforming are smaller in size, thinner in depth, have no fluid associated with them and have overlying drusen. On initial evaluation, your specialist will perform a complete dilated eye exam as well as a series of tests to determine the risk characteristic of your nevus which could include: photography, fluorescein angiogram, optical coherence tomography (with enhanced depth imaging) and ultrasound. Based on these findings, your doctor will make a decision as to how often you should receive a dilated eye exam for your choroidal nevus.
What Is the Treatment for Choroidal Melanoma?
With current therapy, most cases of choroidal melanoma can be treated, thus saving the eye and preserving vision. The first step is performing a biopsy of a suspicious tumor which serves two main purposes:
- Confirming the diagnosis
- Gathering genetic and morphologic characteristics of the tumor, which give us information on how aggressive the tumor might become
Treating the mass involves several different possible approaches including radioactive plaque therapy, transpupillary thermotherapy and external beam radiation (proton-beam). Rarely does the eye (enucleation) or orbital contents (exenteration) need to be removed.
What Are Other Intraocular Tumors?
The most common cause of primary intraocular tumor in children is retinoblastoma. The treatment of these tumors require highly specialized care at large academic centers across the country since the care of these patients require a multi-disciplinary approach with several care providers including ophthalmologic oncologist, medical oncologist and pediatric neuroradiologist. Early signs and symptoms of retinoblastoma include:
- Abnormal red reflex (a whitish appearance in the center of the pupil after a light or flash is shone at the eye – often picked up by a flash photograph)
- Strabismus (an eye pointing in a different direction or wandering)
- Redness
- Swelling
- Eye pain
Other tumors that affect the eye in adulthood include intraocular lymphoma which increases in likelihood with age. Other causes of intraocular tumors are exceedingly rare.