Eye Exams Should Be an Essential Part of Breast Cancer Recovery/Preventive Care

Elissa R. Wedemeyer, O.D., F.C.O.V.D., F.A.A.O.
Glaucoma Specialist

Because of the ocular side effects of medications used to treat breast cancer, a trip to the eye doctor for good baseline data and yearly monitoring of the visual system is warranted.

Some breast cancer cells are hormone-sensitive for estrogen. That means that estrogen can actually boost the growth of breast cancer. Tumors testing positive as estrogen responsive are treated with hormone therapy that stops or slows the tumors by blocking the production or actions of estrogen. Because there are many estrogen receptors in the eye, any treatment option that affects those receptors or estrogen production has the potential for creating negative changes to the ocular and visual system.

Research data in clinical trials shows a 38 to 65 percent reduction in the risk of developing invasive breast cancer with the use of current breast cancer drugs. The benefits of these hormone-based therapies outweigh the ocular side effects. There are three basic actions that these hormonal therapies exhibit. The inhibition of estrogen synthesis is brought about by aromatase inhibitors and are prescribed for post-menopausal women. They can have temporary or permanent action. The brand names of these drugs are Arimidex, Femara and Aromasin.

The class of drugs called selective estrogen receptor modulators (SERMs) can interfere with estrogen binding to the organ specific receptors or act to promote the estrogen actions. The names of those drugs are tamoxifen (Nolvadex), Evista and Fareston. A totally estrogen antagonist receptor blocking drug is Falodex. It is totally antiestrogen and, on binding to the receptor, destroys it.

Patients on the above breast cancer therapy drugs need to be aware of the potential side effects to the eyes. Most of the side effects are the same as in the typical aging process and can be minimal discomfort to sight threatening conditions. The least serious complications can be dry eye brought on by blocking the action of the lacrimal and meibomian glands. These glands are responsible for the production of the tears and oils that keep the ocular surfaces moist and clean. Reduced corneal cell regeneration can contribute to a rough irregular surface that can cause minor to severe blurry vision and eye pain.

Specific types of cataracts, called posterior sub-capsular, can form and cause a quick and severe loss of vision, requiring cataract surgery. White and yellow refractile deposits can occur in the macula, the main area of sight in the retina. These deposits can present a mild reduction in vision to a severe and sudden loss of vision due to fluid in the macula (cystoid macula edema). Small retinal hemorrhages may form due to excessive traction from the shrinking of the vitreous. Vitreous detachments can result in floaters. On a more serious note, sub-clinical swelling of the optic nerve can occur.

All of the above conditions may be detected and monitored by a through eye examination that includes a full check of visual acuity, color vision, retinal, optic nerve and macula evaluations, as well as central visual fields. The retina can be evaluated with optical coherence tomography (OCT), the equivalence of a retinal MRI, that allows the 10 layers of the retina to be imaged and followed at the cellular level for cystoid edema, deposits and tears. Most of the conditions are self limiting when the drugs or dosages are reduced or discontinued.

These breast cancer drugs can prevent the spread of new estrogen responsive tumors from forming, and patients can keep the eyes healthy by continuing to get comprehensive yearly eye examinations.

1. http://www.cancer.gov/cancertopics/factsheet/Therapy/hormone-therapy-breast, Hormone Therapy For Breast Cancer.
2. http://www.nlm.nih.gov/medlineplus/druginfo/meds/a682414.html.
3. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3205820/.
4. Boughton, Barbara, contributing writer, Watch for Ocular Side Effects of Breast Cancer Drugs, Clinical Update, March 2013, aao.org/eyenet.