Beyond Breast Cancer: How Tamoxifen Can Affect Your Eyes

Tamoxifen is a medication primarily known for treating and preventing breast cancer in both men and women. It's a selective estrogen receptor modulator (SERM) and works by blocking the effects of estrogen in breast tissue. This blockade helps stop the growth and spread of hormone-receptor-positive breast cancer cells. However, like many medications, Tamoxifen has its own potential side effects. Some of these can affect the eyes, making regular check-ups with an optometrist vital for people undergoing treatment with this drug.

What Are the Ocular Side Effects of Tamoxifen:

1. Cataract Formation: One of Tamoxifen's ocular side effects is the potential for cataract formation. Cataracts are cloudy or opaque areas in the clear lens of the eye, which can lead to vision loss if left untreated. Research at the University of Southern California indicates a higher prevalence of cataract formation among tamoxifen users than those not on the drug. The research showed a relative risk of 1.4 at three and 1.7 at five years. 

2. Retinal Changes: Tamoxifen can also cause changes to the retina, the thin layer of tissue at the back of the eye that captures light and sends images to the brain. These changes include crystalline retinopathy, where small crystal-like deposits form on the retina, and macular edema, swelling of the retina's central part. Your optometrist can examine these areas with a dilated retinal examination, Optomap Ultra-Widefield retinal or 3D-OCT retinal images. 

3. Optic Nerve Changes: Some reports suggest Tamoxifen might be associated with optic neuropathy. In this condition, the optic nerve is damaged. Optic nerve damage can lead to vision loss, especially if not detected early. These changes can be monitored with 3D-OCT retinal images and computerized visual field testing. 

4. Dry Eyes: Tamoxifen has been reported to cause or exacerbate dry eye symptoms because of the various physiological functions controlled by estrogen. Dry eyes can make the eyes feel scratchy or irritated and may result in blurred vision or problems wearing contact lenses. 

How Often Should People Taking Tamoxifen See an Optometrist?

Given the potential ocular side effects associated with Tamoxifen, it's recommended that people see their optometrist regularly and self-monitor their vision for any changes. Here are some general guidelines:

1. Initial Consultation: Before starting Tamoxifen, seeing an optometrist for a baseline examination is a good idea. This exam will provide a reference point against which future changes can be compared. This initial examination should include the following tests: 

   • Dilated Retinal Examination
     Colour Vision Test
     3D OCT Retinal Scans
     Optomap Ultra-Widefield Retinal Images
     Zeiss Computerized Visual Field Test

   • Please Note: Alberta Health Care covers the cost of these additional tests when required. 

2. Regular Check-ups: Once on Tamoxifen, people should aim to see their optometrist annually. This frequency ensures that any potential ocular changes are detected early. The optometrist might recommend more frequent visits depending on the initial findings or any subsequent issues.

3. When Symptoms Arise: Apart from regular check-ups, if you notice any changes in your vision or experience symptoms like eye pain, increased light sensitivity, floaters, or any other unusual visual phenomena, you should book an appointment with your optometrist as soon as possible.

4. After Discontinuation: Even after stopping Tamoxifen, people should continue seeing their optometrist annually for at least a few years. Some ocular side effects might manifest or persist after the medication has been discontinued. Tamoxifen stays active for up to two weeks after your last dose. However, it can take about three months to flush out of your system entirely.

Conclusion:

While being a vital drug in managing breast cancer, Tamoxifen comes with its set of challenges in ocular health. Regular monitoring and proactive eye care are essential to ensure potential side effects are caught early and managed appropriately.

People on Tamoxifen should be informed about these potential side effects and encouraged to maintain regular communication with their healthcare providers, especially optometrists. This collaborative approach can help ensure the best possible outcomes for people's ocular and overall health.

Disclaimer: The content provided in this blog post is for informational purposes only and is not intended as medical advice, diagnosis, or treatment. Always consult with a qualified healthcare professional regarding any medical condition, treatment, or medication. Helio Optometry and its optometrists do not endorse or take responsibility for any decision made based on the information provided in this article.