Ocular Oncology is a highly specialized branch of medicine that offers expert care in the treatment of various tumors of the eye and surrounding structures.
Eye tumors can affect all parts of the eye and can be either cancerous (malignant) or non cancerous (benign). They can either start within the eye (primary) or spread to the eye from another organ (metastatic). They can threaten the eyesight and can have serious effect on health and life. Hence, the branch of ocular oncology aims at preservation of life by removal of tumor and also aims at preservation of vision.
An ocular oncologist is required for the treatment of eye tumors as they have knowledge of the eye as well as cancer to make sure that the tumor is cured and at the same time the structure and function of the eye is also saved.
Types of Eye Tumors
The most common eyelid tumor is called basal cell carcinoma that grows around the eyes but rarely spreads to other parts of the body. Other types of eyelid cancers that are common include squamous cell carcinoma, sebaceous cell carcinoma and malignant melanoma.
The most common orbital malignancy is Orbital Lymphoma.
The most common malignant (cancerous) tumor inside the eye is melanoma. These tumors can occur in the choroid (layer between retina and sclera–white part of the eye), iris (thin, circular structure in the eye) and ciliary body (the layer of tissue that delivers nutrients to the eye tissues).
The most common malignant tumor inside the eye is Retinoblastoma. Though, it is a life threatening eye cancer, but if treated promptly, the cancer is treatable. Lack of awareness and lack of access to proper treatment makes this cancer sometimes detectable at a more advanced stage.
Signs and Symptoms
People with eye Melanomas often show no symptoms in early stages until an eye specialist looks into the eye with an ophthalmoscope during a routine test. However, as the tumor grows, the following sign & symptoms may be experienced:
- Blurred vision
- Decreased vision and eventually vision loss
- Double vision
- Losing part of the field of vision
- Seeing spots, wavy lines or floaters
- If the tumor continues to grow, it can break the retina causing retinal detachment.
- In case of advanced cancers, patient may have large sized eye ball, redness, swelling and pain.
In retinoblastoma, squinting of the eyes is the most common symptom. There is a whitish (pearl like) or yellowish glow through the pupil. There is a decrease or loss of vision, redness and pain. Retinoblastoma can occur in one or both eyes. This tumor occurs in babies and young children.
How is an Eye Cancer diagnosed?
An eye specialist may have to use many tests to diagnose cancer and find out if it has spread to another part of the body, called metastasis. Though, for most types of cancer, a biopsy is the only way to make a definitive diagnosis of cancer, but, for eye melanoma, biopsy may not be required. Following tests may be done depending on the requirement:
- Eye examination. Most cases of melanoma are found during a regular eye examination using an ophthalmoscope and a slit lamp (microscope with a light attached)
- Eye ultrasound or B-scan of the eye.
- Fluorescein angiography, takes a picture of the blood vessels in the eye. A dye is injected into the patient’s arm that moves through the body and into the blood vessels in the back of the eye. The doctor then takes several quick pictures of the eye.
- Fine needle biopsy. This procedure removes tumor cells from the eye with a needle. This allows the doctor to look at the cells under a microscope.
- Tests for metastases (spread of cancer from eye to other parts of the body): Acomputed tomography (CT or CAT) scan, an ultrasound, Magnetic resonance imaging (MRI) or Positron emission tomography (PET) scan may be done for this.
Treatment for Eye Cancers
Depending on the type and stage of the cancer and other factors, various treatment options for eye cancer can be explored:
The various operations done to treat people with eye cancers include:
- Surgical removal of the tumour: The tumour, specially, if limited in extent can be removed surgically.
- Enucleation: In this the entire eyeball is removed but the muscles and eyelids are left intact. The eyeball is replaced with orbital implant made out of silicone or a substance similar to bone. This is mainly used for larger melanomas. Few weeks after the surgery, an artificial eye is fixed over the orbital implant and under the eyelids. The artificial eye will match the size and color of the remaining eye.
- Evisceration: In this the eye contents are removed, leaving the white part of the eye (sclera).
- Orbital Exenteration: It involves removal of the eyeball and some surrounding structures such as parts of the eyelid, muscles, nerves and other tissues inside the eye socket. This surgery is not common, but it might sometimes be used for melanomas that have grown outside the eyeball into nearby structures. Similar to enucleation, an artificial eye might be placed in the socket after surgery.
- Eyewall Resection: This requires cutting into the eye to remove a tumor e.g. melanoma. This operation can be quite difficult to perform.
(b) Radiation Therapy: It involves treating tumor with radiations, based on size and location of the tumor. It is done in conjunction with the radiation oncologist.
(c) Laser Therapy: Lasers are highly focused beams of light that can be used to destroy body tissues. Laser therapy is sometimes used to treat intraocular (eye) melanoma.
- Transpupillary Thermotherapy (TTT) : This is the most common type of laser treatment for eye melanoma. It uses infrared light to heat and kill the tumor. It works well for small choroidal melanomas because the melanin pigment in these cells absorbs the light energy from the laser. TTT is only used to treat small choroidal melanomas because the laser might not be able to reach the deeper parts of thicker melanomas.
- Laser Photocoagulation: This treatment uses a highly focused, high-energy light beam to burn tissue. It can be effective for very small melanomas. Several laser treatments are usually given 6 or 8 weeks apart to treat a tumor.
Chemotherapy (chemo) is the use of drugs to treat cancer. The drugs can be injected into a certain part of the body (such as the eye) or they can be injected into a vein or taken by mouth to reach throughout the body, making this treatment very useful for cancers that have spread. Chemotherapy can be useful for treating intraocular (eye) lymphoma, but it is used less often for intraocular melanoma.
Depending on the type and the stage of the lymphoma, chemo may be used alone or in combination with radiation therapy.
(e) Targeted Therapy
For treating melanoma that has spread outside the eye, standard chemotherapy drugs may not be very helpful. For those, newer types of drugs are. These are immunotherapy drugs or targeted drugs.