Introduction
Ocular toxicity from chemotherapy is a primary side effect that can lead to visual impairment and other eye-related abnormalities in the cancer patient. Chemotherapy drugs are designed to target cancer cells, but these drugs can also affect the body's normal cells, including those in the eye. The exact cause of ocular toxicity from chemotherapy is not fully known, but it can be caused by direct drug toxicity to the eye tissues or damage to the blood vessels that supply the eye. The type and severity of ocular toxicity can vary according to the dose, duration, and use of chemotherapy drug treatment. Common ocular toxicity includes blurred vision, conjunctivitis, decreased color vision, and corneal ulcers. In severe cases, it can lead to optic nerve damage, retinal damage, and vision loss. The healthcare provider may prescribe eye examinations and adjust the dose to reduce the risk. In the event of toxicity, management requires a multidisciplinary approach to reduce the damage from ocular toxicity.
What Is Chemotherapy?
Chemotherapy is a type of cancer treatment. It includes drugs to destroy cancer cells. These drugs are designed to kill cancer cells but can also affect normal cells. Chemotherapy can be given orally, intravenously, or topically. The route of administration of drugs depends on the stage and type of cancer and the patient's health status. It can be used in combination with radiation therapy and surgery. These drugs also control the cancer growth that spreads to other parts of the body. It is effective in treating cancer but also causes side effects.
What Are the Causes of Ocular Toxicity From Chemotherapy?
Chemotherapy drugs can cause ocular toxicity, which can lead to vision loss and damage to the eye. The cause of ocular toxicity depends on the dose, type, and duration of the chemotherapy drug used. It also depends on the patient's health status. The causes of ocular toxicity from chemotherapy are as follows:
-
Direct Toxicity to the Eye: Some chemotherapy drugs can directly damage the tissues and cells of the eye, including the cornea, optic nerve, and retina. The drugs include Methotrexate, Vincristine, and Cisplatin.
-
Alterations in Tear Production: Chemotherapy drugs can interfere with tear production, leading to corneal damage and dry eyes. The drugs contributing to the condition include Tamoxifen and Cytarabine.
-
Immune System Effects: Chemotherapy drugs and treatments can suppress the patient's immune system. It makes the eye more prone to infection and inflammation. This can lead to major eye conditions, including uveitis, conjunctivitis, and keratitis.
-
Vascular Damage: Some chemotherapy drugs can cause damage to the blood vessels, leading to a decrease in blood flow to the eyes and resulting in retinopathy, optic neuropathy, and ischemia (blood flow to the body part is restricted). The drugs causing the condition include Vincristine and Cisplatin.
-
Metabolic Effects: Chemotherapy drugs can cause metabolic imbalances that affect the eyes, including hypocalcemia, hypomagnesemia, and hyperglycemia. The metabolic imbalance can lead to retinopathy, cataracts, and optic neuropathy (damage to the optic nerve).
How Common Is Ocular Toxicity From Chemotherapy?
Ocular toxicity is a common side effect of chemotherapy. The severity and incidence depend on the dose and duration of treatment. The incidence of ocular toxicity is difficult to estimate due to the variation in the study method and population. The incidence is one to three percent in patients receiving chemotherapy. Other people have reported high rates of up to 20 percent.
What Eye Problems Are Associated With Chemotherapy?
Chemotherapy can lead to eye problems, including:
-
Dry Eyes: Chemotherapy can interfere with tear production, leading to irritated or dry eyes. It can cause redness, discomfort, and a feeling of grittiness in the eyes.
-
Conjunctivitis: The condition is also known as pink eye. It is an inflammation of the tissue that covers the white part of the eye in and around the eye. Chemotherapy treatment can cause conjunctivitis, which can lead to itching, redness, and discharge from the eye.
-
Blurred Vision: Chemotherapy can make it difficult for a person to focus properly, which can result in blurry vision. It makes it difficult for the person to drive, read, and perform tasks that require vision.
-
Cataracts: Chemotherapy can cause cataracts, which can lead to blurred vision, difficulty seeing in low light conditions, and glare.
-
Retinopathy: Chemotherapy treatment can damage the retina. The retina is a light-sensitive tissue layer of the eye that sends signals to the brain. The condition can lead to a blind spot, reduced vision, and distorted vision.
-
Optic Neuropathy: Chemotherapy can damage the optic nerve. This can lead to side vision loss.
What Are the Symptoms of Ocular Toxicity From Chemotherapy?
The symptoms of ocular toxicity from chemotherapy include blurred vision, loss of color vision, visual field defects, night blindness, eye pain, discomfort, and photophobia (pain or discomfort when exposed to bright light). The symptoms vary depending on the severity and duration of optic toxicity.
How Can Ocular Toxicity From Chemotherapy Be Diagnosed?
The healthcare provider may ask about the patient's medical history and any chemotherapy treatment or medications leading to eye problems. In addition, the eye doctor may prescribe various diagnostic tests, including:
-
Visual Acuity Test: The eye doctor may measure the person's capability to see objects at various distances.
-
Color Vision Test: The test assesses the person's ability to distinguish colors.
-
Optical Coherence Tomography: The doctor may prescribe the test to detect changes in the retinal thickness or other abnormalities. The test may create detailed images of the retina.
-
Electroretinography: In response to light stimulation, the test measures the electrical activity of the retina.
How Can Ocular Toxicity From Chemotherapy Be Managed?
The healthcare provider may manage the symptoms depending on the severity and type of eye problem. If chemotherapy is the cause of the condition, the doctor may adjust the dose and change the medications to reduce the side effects. In addition, eye drops or ointments may manage dry eyes or conjunctivitis. The doctor may advise the patient to wear protective eyewear, such as goggles, to protect the eyes from bright light. Certain nutritional supplements, such as omega-3 fatty acids, may reduce the risk of ocular toxicity. A cataract may require surgical treatment.
Conclusion
Ocular toxicity from chemotherapy can impact the patient’s quality of life. The eye abnormalities include dry eyes, cataracts, retinopathy, conjunctivitis, and optic neuropathy. The symptoms include blurred vision, loss of color vision, night blindness, pain, and discomfort in the eye. Early detection and treatment may help in minimizing the side effects and preserve vision. Treatment may include discontinuing or adjusting the dose of chemotherapy drugs. The healthcare provider may advise the patient who is undergoing chemotherapy to have a regular eye examination. Protective eyewear and a nutritional supplement may reduce the risk of ocular toxicity.
