It’s very rare for kidney cancer to spread to the eyes — there have been just over 100 cases documented in research. When it does happen, it’s known as ocular metastasis.

Although ocular metastasis is rare, it can happen. People with kidney cancer have other good reasons to pay close attention to their eye health and vision. Some kidney cancer treatments and related health conditions can also affect the eyes.

Here are the potential eye problems that can happen during and after kidney cancer, along with the reasons why regular eye exams are a must.

What Should You Know About Eye Metastasis?

If you live with kidney cancer, it’s important to be aware of the different ways it can spread. Kidney cancer can come back (recur) even if your tumor was limited to your kidney and you had nephrectomy surgery to remove it. If kidney cancer recurs, it may be metastatic.

Why Ocular Metastasis Is Rare

In general, the eyes aren’t a common place for cancer to spread. If tumors metastasize, cancer cells travel to the lymph nodes first. When cancer is found in the lymph nodes, it goes from stage 1 to stage 2. From there, it can spread to other places through the lymphatic system, which includes fluid that flows throughout the body.

However, the eyes aren’t directly connected to the lymphatic system. Kidney cancer that’s not found until it’s in distant organs like the eyes is considered stage 4. That means it’s an advanced form of metastatic cancer.

Other types of cancer have a higher chance of spreading to the eyes than kidney cancer. Renal cell carcinoma (RCC) is the most common form of kidney cancer. It’s also the most likely kidney cancer to spread to the eyes. However, among all eye metastasis cases, only 2 percent come from RCC.

Where It Happens

If kidney cancer spreads to the eyes, it’s more likely to go to specific areas. The eye structures typically affected are part of the uveal tract, which includes the:

• Choroid — A layer of tissue filled with blood vessels
• Iris — The colored part of the eye (also known as the uvea)
• Ciliary body — A ring of muscles that change the lens shape and make fluid

Who It Affects

Medical reports have found kidney cancer spread to the eye in people of many ages, from a 2-week-old infant to an 81-year-old. Eye metastasis is more common in men, with 3.4 men diagnosed for every woman with eye metastasis. Men are also more than twice as likely as women to have kidney cancer.

When It’s Discovered

Usually, people are diagnosed with kidney cancer before they’re diagnosed with eye metastasis. Of the small number of recorded cases, 67.4 percent of those with eye metastasis had a known history of RCC. However, in 32.6 percent of cases, eye problems were the first sign of RCC.

What Are the Symptoms of Eye Metastasis?

When eye metastasis does happen with kidney cancer, these are the symptoms that have been noted.

1. Red or Dry Eyes

Metastatic renal cell carcinoma that’s spread to the eyes may cause eye redness and dry eyes. Dry eyes may become irritated and itchy. They can also make it feel like there’s something in your eye.

2. Thickening in One Eye

Thickening of the eye tissue is another symptom documented in people with eye metastasis of RCC. Dryness and eye irritation can make thickening worse.

Thickening can develop in the inner or outer corners of the eye. In some cases, it can get in the way of normal blinking.

3. Vision Loss or Blurry Vision

Decreased visual acuity (sharpness) and blurred vision are also possible symptoms of eye metastasis. But you shouldn’t jump to conclusions if your vision isn’t as clear as it used to be.

Many different issues can contribute to vision changes. Scheduling an eye appointment can help you determine the cause and whether you need treatment.

4. Double Vision

Some people with kidney cancer metastasis have had double vision. With double vision, you see two images of the same object.

Double vision can make it harder to walk or drive safely because it affects your depth perception. It’s a pretty common symptom that can be caused by many health conditions apart from cancer metastasis. In fact, double vision is one of the top reasons people go to the emergency room.

5. Bulging Eyes

An eye that bulges is another possible sign that kidney cancer has spread to the eye. Most often, bulging eyes are caused by thyroid disease. However, it can also be a symptom of different types of tumors.

Double vision and dryness can accompany bulging eyes. If you notice multiple symptoms affecting your eyes, mention each of them to your healthcare provider.

Can Kidney Cancer Treatment Affect the Eyes?

Several cancer treatment options can affect your vision and eye health. Knowing your risks can help you be mindful of any possible side effects, both now and in the future.

Side Effects of Radiotherapy

If you’ve had radiation therapy in locations close to your eyes or your whole body, there’s a risk of eye damage. Harm from radiation can lead to dry eyes and vision loss.

Risk of Cataracts

Some anticancer medications and steroids raise the risk of cataracts. Symptoms of cataracts include:

• Impaired night vision
• Blurry vision
• Double vision (affecting one eye)
• Faded color vision
• Seeing halos surrounding objects
• Sensitivity to light

Dialysis

If you’re on dialysis because of kidney failure or having both kidneys removed, you have a higher risk of eye disease. You may have changes in eye pressure that can put your vision at risk.

Why Are Regular Eye Exams Important?

The eyes are vulnerable, especially as people with cancer are living longer due to advances in treatment. Aside from eye metastasis, there are additional risks to keep in mind.

Fortunately, many of these concerns are preventable or treatable, as long as you follow up with your eye doctor.

Risk of Paraneoplastic Syndromes

Paraneoplastic syndromes (PNS) can also affect the eye. PNS happens when cancer causes the immune system to attack healthy tissue. It can lead to serious eye problems, including blindness, a detached retina, and cataracts.

PNS is associated with various cancers, including (although rare) clear cell renal cell carcinoma. Early detection of PNS is essential for treatment to reduce the risk of lasting effects.

Getting Your Eyes Checked

Regular eye exams are essential. This is especially true for those with clear cell RCC who are at risk for metastasis and PNS.

If you’ve completed treatment for kidney cancer, eye-related side effects can still develop years later. Your oncology team can recommend how often you should get your eyes checked based on your medical history.

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Have you noticed any changes to your eyes or vision since being diagnosed with kidney cancer? Let others know in the comments below.