Chemo, radiation and the eyes
Cancer can be treated in several ways, including chemotherapy (also referred to as “chemo”) and radiation therapy. However, these treatments can cause eye-related side effects, ranging from temporary changes to permanent issues like vision loss. Treatment and support groups are available to help manage these side effects.
Chemotherapy destroys cancer cells with medicine. This medicine can be given as a pill or an injection, but it’s typically given via infusion. The medicine then spreads through the body so it can destroy cancer cells that have spread from the original cancer location.
Radiotherapy destroys cancer cells using radiation. It targets the specific area of the cancer.
How chemotherapy affects the eyes
Chemo can affect your eyesight and eye health in several ways. The type of chemotherapy used for treatment depends on:
- The type of cancer
- The stage of cancer
- The location of the cancer
- The health of the patient receiving chemotherapy
When chemotherapy destroys cancer cells, it may also destroy other cells in your body. The damage to healthy cells may cause side effects.
Common eye-related side effects from chemotherapy
Chemotherapy can cause a range of side effects in the eyes. Sometimes the chemotherapy drugs can cause a larger systemic effect (like anemia) that leads to eye symptoms. These effects depend on the specific drugs used for chemo and how these drugs interact with the body.
Inflammation inside the eye or conjunctivitis
Chemo can cause irritation and inflammation in the middle layer of your eye (the uvea). This is called uveitis. Some drugs may also cause conjunctivitis. Conjunctivitis (or pink eye when infectious) is when the conjunctiva, the clear membrane that lines the inside of your eyelids and covers the white part of your eye (sclera), becomes inflamed.
Vision changes
Chemo may affect your eyesight. Some common symptoms are:
- Blurred or dulled vision
- Seeing halos or rings around lights
- Less clear vision
- Areas of vision that are missing
Dry or watery eyes
Chemo drugs may cause dry eye syndrome (also called dry eye disease) or make your eyes more watery. These symptoms can happen because of a reaction to the drug or because the drainage system inside the eye becomes blocked.
Eyelash growth
Cancer treatments can also affect eyelash growth. It can cause trichomegaly, which is when your eyelashes grow too long, or trichiasis, which is when your lashes grow inward. Trichiasis can lead to corneal abrasion, watery or teary eyes, and general irritation.
Potential long-term vision changes from chemo
When chemo causes blurry vision, dry eye and other side effects, they often can improve or go away in the weeks and months after treatment ends. However, it’s possible for these effects to linger and become intermittent to permanent. Chemotherapy may also cause some eye conditions to develop that can lead to further eyesight changes.
Cataracts
Corticosteroids, which are often given alongside chemotherapy to manage side effects, can independently contribute to cataract formation. Cataracts are when the natural crystalline lens of your eye becomes cloudy. This leads to impaired vision.
Glaucoma
Glaucoma is a disease that damages the optic nerve. The optic nerve is responsible for communicating with the brain to process vision. When damage to the optic nerve occurs, it can lead to permanent vision loss. The effects of some chemotherapy drugs — particularly steroids, used in conjunction with chemo — can damage the optic nerve and lead to glaucoma.
Retinopathy
The retina is the layer of tissue at the back of the eye that senses light, allowing you to see. Certain cancer drugs can affect the retina, causing different types of retinopathy (damage to the retina) leading to deposits, swelling, retinal detachment or in rare cases, fluid accumulation that affects central vision.
How radiation therapy can affect the eyes
Radiotherapy involves the use of radiation to kill cancer cells. It’s usually applied to the cancerous area using a beam. The radiation damages the cancer cells’ DNA, which hampers their ability to grow and multiply.
Radiation therapy tends to affect the part of the body receiving the radiation. It’s more likely to affect your eyes if the radiation is treating an area near the eye, like in head and neck cancers. These effects can include damage to parts of the eye, such as the cornea (the dome that covers the front of the eye). Other parts of the eye that can be affected include the:
- Optic nerve
- Retina
- Lens
Some effects of radiation therapy may not appear for months, years, or even decades after treatment, depending on the dose and the area treated.
Common eye-related side effects from radiation therapy
Radiation can affect the skin around the eyes, causing blisters and peeling. Sometimes this affects the eyelids, most commonly causing inflammation (blepharitis). Radiation therapy may also cause loss of eyelashes, which can be temporary or permanent.
Dry eyes are especially common, and watery eyes can also be a side effect. In some cases, significant dry eye from radiation treatment may lead to corneal irritation or inflammation later.
Radiotherapy can also lead to:
- Blurry vision
- Changes in color perception
- Sensitivity to light
Possible long-term vision changes from radiation
Radiotherapy can also cause eye conditions that may not appear right away, like:
- Neovascular glaucoma – Radiation can cause neovascular glaucoma that happens as a result of new blood vessel growth.
- Cataracts – Destruction of cells in the natural lens means that lens fibers can’t be removed like normal, leading to cataract formation.
- Retinopathy – Radiation can damage the blood vessels in the retina over time.
- Radiation optic neuropathy (RON) – Radiation causes blood vessels in the optic nerve to be damaged, leading to ischemia (reduced blood supply), vascular occlusion and subsequent vision loss.
The timing of these side effects depends on the type and intensity of the radiation therapy. Eye-related side effects caused by radiotherapy can be permanent. This makes it very important to talk to your eye doctor if you experience any visual symptoms.
Managing eye health during cancer treatment
Some eye side effects of chemo and radiation are mild and can be managed with the help of your eye doctor and care team. There are also organizations available to provide support and treatment for cancer care and eye health.
Preventive measures
Early treatment makes it much easier to prevent more serious conditions. It’s important to let your eye doctor and care team know if you’re experiencing any side effects. Regular examinations and monitoring throughout treatment mean you have a chance of catching a serious condition much earlier.
Coping strategies
There are numerous options for managing symptoms. Dry eye syndrome, for instance, can be treated with eye drops or warm compresses. You can also use artificial tears, prescription eye drops or other treatments recommended by your doctor. If you’re sensitive to light, it may help to avoid bright lights and wear tinted glasses.
For more serious effects on your eyesight, your eye doctor might refer you to rehab, low vision care or occupational therapy.
Support networks
There are many support groups for people undergoing cancer treatment, including for people who may be suffering vision or eye-related side effects. CancerCare’s online search tool has information on organizations that offer assistance to people living with cancer.
Organizations like Lions Club International and EyeCare America help people access free and low-cost eye exams and prescription glasses.
Regular eye exams during and after treatment are essential
Regular comprehensive eye exams are important for preventing long-term damage to your eyes and vision. You may be required to have an exam prior to starting a certain cancer treatment, followed by regular eye exams throughout your treatment. The frequency will depend on your treatment and any side effects you experience. It’s important to let your oncologist, ocular oncologist (an ophthalmologist who specializes in diagnosing and treating cancers of the eye, eyelid and eye socket) and eye doctor know if you notice any problems.
How soon after chemo can you have your routine eye exam?
It's important to keep up with routine eye exams even after chemo or radiation treatments end. This allows your eye doctor to monitor any new or existing changes in your eyes and vision.
If you need a new eye prescription, you may need to wait a certain amount of time before you update your prescription. How long you should wait and how often you should schedule follow-up exams may vary based on your type of treatment and cancer.
Your eye doctor will work with your medical care team to give you appropriate guidance.
When to contact your eye doctor right away
Some eye symptoms during or after cancer treatment may need prompt attention rather than waiting for your next scheduled visit. Reach out to your eye doctor soon if you notice:
- Sudden vision changes or loss of vision in one or both eyes
- A new shower of floaters, flashes of light, or a shadow or curtain crossing your field of view
- Severe eye pain, especially with halos around lights, nausea or headache
- New double vision, a drooping eyelid or trouble moving one of your eyes
- Worsening redness, light sensitivity or eye pain that isn't easing
These can sometimes signal conditions like retinal damage, raised eye pressure or inflammation that respond best when caught early. Your eye doctor and care team can coordinate on next steps from there.
