When you or a loved one are going through cancer treatment, the sheer number of medications and their potential side effects can feel entirely overwhelming. Not all cancer treatments affect the body in the same way, and knowing exactly what to expect can ease a great deal of anxiety.
While you might be well-prepared for fatigue or hair loss, the ways these powerful drugs affect your eyes are often less talked about. By demystifying how different treatments impact your vision, we hope to give you the knowledge you need to feel more in control of your health journey.
Classical Chemotherapy vs. Targeted Therapies
Traditional or "classical" chemotherapy works by attacking fast-growing cells throughout the body. Because the cells in your tear glands naturally turn over very quickly, they often get caught in the crossfire.
Drugs known as taxanes, such as docetaxel and paclitaxel, act directly on these tear glands, causing a drop in tear production that severely dries out the eye surface. The good news is that this uncomfortable dryness is usually temporary and resolves within a few months after your treatment ends.
However, newer treatments like targeted therapies and immunotherapies act differently and can sometimes require much closer attention. For example, if you are being treated for multiple myeloma with a specific targeted therapy called belantamab mafodotin, regular and continuous eye monitoring is a mandatory part of your standard treatment protocol. This is because the drug specifically impacts the delicate cells on the surface of your eye.
Hormone Therapy and Radiation
Hormone therapies and radiation come with their own unique set of rules for eye care. Tamoxifen, a hormone therapy frequently used for breast and ovarian cancer, can cause vision changes if taken at higher doses over long periods.
It can lead to small opaque spots on the cornea, crystalline deposits in the retina, and sometimes swelling in the macula, which is the part of your eye responsible for sharp, central vision. If you are taking tamoxifen, you must have dilated eye exams at least once a year to monitor for these specific changes.
Radiation therapy, particularly when directed near the head or neck area, can also profoundly affect your eyes. It can unintentionally damage the retina and the optic nerve. Crucially, these delayed side effects might not appear until up to 18 months after your radiation treatment has concluded.
Radiation in this area is also known to cause the permanent loss of your eyelashes. Because these changes can be permanent, frequent check-ups are essential.
When to Act Fast: The "Same-Week" Rule
While many eye symptoms like mild dryness can be managed at home, there are certain warning signs that require immediate professional attention. If you experience any of the following, you should not wait for your next scheduled check-up; instead, follow the "same-week" rule and see an eye doctor immediately.
Act fast if you experience distorted vision, such as straight lines looking bent or wavy. You should also seek urgent care if you suddenly have trouble seeing the color red, as this is often the very first sign of optic nerve damage. Other immediate red flags include a sudden difference in how clearly one eye sees compared to the other, painless vision loss, or the sudden appearance of new flashes of light, dark spots, or floating "flies" in your field of view.
Tracking Changes and Staying Informed
One of the best ways to keep track of these changes is by starting a health care journal. Whenever you notice your eyes feeling unusually dry, or if you experience a brief moment of blurred vision, write down the time and the severity.
Bring this journal with you to your appointments so you can give your care team a clear picture of what you are experiencing. It is also incredibly helpful to bring a friend or family member to your appointments to help you remember the doctor's advice.
Your Safe Space at KSA Vision Clinic
At KSA Vision Clinic, we understand that navigating life during and after cancer is a monumental task. We are here to act as a supportive, caring part of your medical team.
When you visit us, it is incredibly important that you tell your eye doctor about every drug you are taking, or even the ones you stopped taking years ago. Because some side effects take a long time to show up, having your complete medical history allows us to give you the best possible care.
If you have always wanted to be free of glasses, you might be wondering if elective laser eye surgery is an option for you after you beat cancer. The answer is an enthusiastic yes, but you must be patient. Your eyes need to be perfectly calm and your tear film completely stable for the surgery and healing process to be successful.
That is why we wait until your cancer treatments are completely finished and your eyes have been settled for several months before determining the right time for a Flow3 eye exam. KSA is a safe, welcoming space to discuss all of these changes. Please remember, never stop your cancer treatment on your own because of eye discomfort—let us handle your vision, while your oncologist handles your recovery.
Sources: National Cancer Institute on eye problems during cancer treatment, Cancer Research UK on cancer drug eye side effects, American Academy of Ophthalmology on cancer drugs and eyes.
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