What Your Eyes Reveal About Your Health

By Dr. Mercola

Because dozens of diseases and illnesses are known to show symptoms in your eyes, ophthalmologists and optometrists are often among the first to help you recognize certain medical conditions.¹ An internal study of 120,000 patients by insurance company VSP Vision Care highlights the value of vision care. Their data suggests an eye exam was the first indicator of problems in:²

• 62 percent of imbalanced cholesterol cases
• 39 percent of high blood pressure cases
• 34 percent of diabetes cases

If you are unsure what your body might be trying to tell you with respect to changes in your eye health and vision, you’ll want to continue reading. While your eyes may be a window to your soul, they can also reveal health problems elsewhere in your body.

Changes in Blood Vessels Within Your Eyes Can Predict Future Memory Loss

A new study published in the medical journal Neurology³ once again links your eye health to the potential future risk of memory loss. As reported by CNN Health,⁴ the study suggests small changes in the blood vessels within your eyes at age 60 can predict your likelihood of experiencing cognitive decline during the next few decades of life.

Because the very small blood vessels in your brain are unable to be seen using standard brain imaging techniques, such as magnetic resonance imaging (MRI), researchers hypothesized studying blood vessels in the eye might provide clues about what’s happening in the brain.

Prior studies have already affirmed that diseases of your vascular system put you at increased risk of cognitive impairment as you age. The current study tracked 12,317 men and women aged 50 to 73 over a 20-year period to test the hypothesis that retinal vascular signs are strongly associated with cognitive decline.⁵

At the onset, participants were evaluated for their memory and thinking skills. Two additional rounds of tests occurred during the next 20 years. Three years into the study, researchers used a special camera to take photos of each person’s retina, thereby providing a snapshot of what is going on in the microvasculature in the eye. From that one measure, scientists can identify retinal signs indicative of retinopathy, also known as damage to the retinal blood vessels. Those tests revealed:⁶

• 95 percent of participants showed no signs of damage to their retinal blood vessels
• 3 percent had mild retinopathy
• 2 percent had moderate to severe retinopathy

After analyzing the data,⁷ the researchers noticed participants with moderate to severe retinopathy were more likely to score significantly lower on memory and thinking tests than their healthy-eyed peers. (While results were stronger for people with diabetes, the linkage was equally significant for those who did not have diabetes.)

These participants, in fact, saw their average test scores decline by 1.22 standard deviation units during the 20-year study. In contrast, participants with healthy eyes experienced declines of 0.91 standard deviation units.

About the outcomes, the study authors stated, “Retinopathy was associated with accelerated rates of 20-year cognitive decline. These findings support the exploration of more sensitive measures in the eye … which may provide surrogate indexes of microvascular lesions relevant to cognitive decline in older adults.”⁸

If Your Eyes Are Unhealthy, It’s Likely Your Brain May Be Unhealthy Too

Dr. Rachel Bishop, chief of the National Eye Institute’s consult service, who was not involved in the study, affirmed the research results, saying:⁹

“If the retinal blood vessels are unhealthy, there’s every reason to think the brain blood vessels are unhealthy as well. The blood vessel supply is essential to all function — the function of all organs — and so if the blood vessels are unable to do their job, there’s no way the brain can be functioning as well as a brain that has a good [blood] supply.”

When asked for her opinion related to screening the eye and retina for potential negative conditions in the brain, such as memory loss, Bishop said, “I share a common hope we could detect things early enough and have interventions early enough to change the course of a negative [brain] event.”¹⁰

Since your brain is neatly tucked inside of your skull, the eyes are, in effect, the only part of the brain that can be seen directly. This happens when your eye doctor uses an ophthalmoscope and shines a bright light into your eye as part of an eye examination. The light reveals your retina and blood vessels and can also detect any potential issues with your optic nerve, which carries visual messages from your retina to your brain via electrical impulses.

“Looking in an eye really is a fabulous experience,” says Dr. Charles Wilkinson, a retina specialist and past president of the American Academy of Ophthalmology. “It’s the only place you can see blood vessels bouncing along their merry way, [and] you can see the optic nerve, which is part of the brain.”¹¹

What Else Can Your Eyes Tell You About Your Health?

Beyond cluing you into a possible future risk of memory decline, your eye health has been associated with a growing list of conditions and diseases that can tell you a lot about your health.

Dr. Justin Bazan, an optometrist and medical adviser to the nonprofit The Vision Council, highlights the importance of studying the blood vessels found in your eyes. “They do have a direct link and correlation to systemic disease,” he said. By tracking eye changes that occur with disease, says Bazan, it may be possible to predict cardiovascular events, such as stroke, as well as mental changes related to conditions like Alzheimer’s disease.¹²

For that reason, Bazan suggests you undergo routine eye exams for more than just obtaining new glasses or refilling your prescription for contact lenses. He believes these appointments are also opportunities for you to learn more about the health of your eyes and how your ocular health affects your overall health and well-being. Some of the diseases known to affect your eyes include the following:¹³

Cancer

While you or your doctor will likely detect signs of malignancy before it would be uncovered in an eye exam, cancers of the breast, as well as leukemia and lymphoma, often signal their presence in your eyes.

Bazan explains that one of the most common types of cancer detected involves the basal cells in the sensitive skin surrounding your eye.  Another devastating cancer is ocular melanoma — cancer in the cells of the eye. Although it is uncommon, it “definitely does occur, and it is devastating,” Bazan says.

Diabetes

Fluctuations in vision, such as blurry vision, may be a sign of diabetes. “Diabetes can be seen in the eyes,” Bazan said. “[People] may experience periods where their blood sugar is out of control, which causes changes to the lens inside the eye, and when you cause changes to the lens, it ultimately impacts vision.” Although similar vision changes can be attributed to aging, it’s best to rule out diabetes as a potential cause.

High blood pressure

High blood pressure is also easily observed in your eyes, notes Bazan. Damaged blood vessels can cause hemorrhages and leaking, both of which are visible during eye exams.

Cholesterol imbalance

“High cholesterol is one of the easiest things to pick up in an examination because it’s on the front of the eye,” states Bazan. It’s common for heart conditions caused by a buildup of plaque to raise concerns during an eye exam, he says.

When plaque builds up in your carotid artery, Bazan notes, “sometimes those little plaques will break off and then travel into the eye, where they clog arteries in the eye, and that leads to very obvious changes to the vascular structure in the back of the eye.” While a diagnosis could not be made based on the eye exam alone, it’s likely your doctor would recommend an MRI and other tests to troubleshoot the condition.

Lupus

Uveitis, or red and swollen eyes, occurs as a result of lupus and other autoimmune diseases. Other effects lupus can have on your eyes include: blood vessel changes in your retina, changes in the skin around your eyelids, damage to the nerves in the muscles controlling eye movement and dry eyes.¹⁴ “If you have a condition where there is systemic inflammation, it is almost always going to manifest in the eye as uveitis,” Bazan said.

Multiple sclerosis (MS)

When examining the eyes of an MS sufferer, the doctor will notice a change in the color and appearance of the optic nerve. According to the National Multiple Sclerosis Society, a vision problem is often the first symptom of the disease:¹⁵

“The visual symptoms that occur in MS may be the result of optic neuritis — inflammation of the optic nerve — or lesions (damaged areas) along the nerve pathways that control eye movements and visual coordination. Optic neuritis may result in blurring or graying of vision, or blindness in one eye. A scotoma or dark spot may occur in the center of the visual field.”

This would lead to more thorough testing to confirm the diagnosis of MS.

Sexually transmitted diseases (STDs)

Sometimes eye problems like conjunctivitis (also known as pink eye) that are not easily resolved may be an indicator of a bigger problem. “My first patient in optometry school had conjunctivitis … that was unresponsive to [the] typical eye drops used to treat it,” Bazan stated. After further testing, the patient was diagnosed with the STD chlamydia.

Certain types of herpes infection may also cause conjunctivitis. Bazan says he’s seen syphilis as well, which can cause your pupil to turn a grayish color. Due to its impact on your white blood cells, HIV also can cause visible changes to your retina.

Thyroid disease

Thyroid disease can be revealed in your eyes in more than one way. Dry eye disease can be associated with thyroid disease, notes Bazan, because your thyroid controls the hormones responsible, in part, for producing teardrops.

Thyroid conditions can also cause your extraocular muscles, which are responsible for controlling eye movement, to become stiff and enlarged. Bulging eyes are a sign of Graves’ disease, an autoimmune disorder that causes hyperthyroidism.

Strategies to Help You Improve and Safeguard Your Vision

Below are several recommended steps you can take to help improve and safeguard your vision. Most of these steps involve vision-related dietary changes.

Avoid trans fat. A diet high in trans fat appears to contribute to macular degeneration by interfering with omega-3 fats in your body. Trans fat is found in many processed foods and baked goods. Some high trans fat foods to avoid include cookies, crackers, doughnuts, french fries, fried chicken, margarine, pastries and shortening.

Care for your cardiovascular system. As mentioned, high blood pressure can cause damage to the small blood vessels on your retina, obstructing free blood flow. One of the primary ways to maintain optimal blood pressure is to dramatically reduce your fructose intake. While your doctor may be down on salt, sugar is worse on your blood pressure than salt.

My standard advice is to keep your total fructose consumption below 25 grams per day, including fructose from fruit. If you have diabetes, heart disease, high blood pressure or insulin resistance, you’d be wise to restrict your fructose to 15 grams or less per day until your condition improves.

Eat dark green leafy vegetables. Studies have shown a diet rich in dark leafy greens (preferably fresh, organic) promotes eye health. Consuming high amounts of carotenoid-rich vegetables, especially ones rich in lutein and zeaxanthin, also encourages healthy vision.

Get plenty of healthy omega-3 fat. Consuming omega-3 fats has been shown to be protective of healthy vision. Unfortunately, due to widespread pollution and farmed fish, you should restrict your choice of fish to anchovies, sardines, herring or wild Alaskan salmon. If you must use a supplement, I recommend krill oil, which also contains astaxanthin, a potent antioxidant I’ll discuss below.

Normalize your blood sugar. Excessive sugar in your blood can pull fluid from the lens of your eye, affecting your ability to focus. It also can damage the blood vessels in your retina, which will obstruct blood flow.

Quit smoking. Smoking increases free radical production throughout your body, putting you at risk for less-than-optimal health in many ways, including the risk of vision problems. If you need an incentive to stop, check out the side effects of smoking, along with some tips on how to quit.

Antioxidants: Your Greatest Allies for Healthy Eyes

Antioxidants neutralize dangerous free radicals throughout your body, including your eyes. Four antioxidants known to benefit your eyes are: astaxanthin, black currant anthocyanins, lutein and zeaxanthin. Lutein and zeaxanthin, found in high concentrations in the macula lutea, are believed to serve two primary roles: absorb excess photon energy and quench free radicals before they damage your lipid membranes.

The highest concentration of lutein in your eyes is in your macula — the tiny central part of your retina responsible for straight ahead and detailed vision. More specifically, lutein is found in the macular pigment and is known for helping to protect your central vision. Lutein is a naturally occurring carotenoid, found in green leafy vegetables, as well as yellow and orange fruits and vegetables.

Some of the top lutein-containing vegetables (in order of lutein content) are kale (raw and cooked), as well as cooked spinach, collards, turnip greens and green peas. Pastured organic egg yolk is also an excellent source of both lutein and zeaxanthin. While lutein and zeaxanthin benefit your eyes, astaxanthin has emerged as the best carotenoid for eye health and the prevention of blindness. Astaxanthin provides protective benefits against a number of eye-related problems, including:

Astaxanthin also helps maintain appropriate eye pressure, energy levels and visual acuity. Because the above list includes several of the leading causes of blindness in the U.S.,¹⁶ this powerful antioxidant becomes increasingly important.

As mentioned earlier, krill oil is a great source of both healthy omega-3 fat and astaxanthin. If you want to give astaxanthin a try, I recommend starting with 2 to 4 milligrams per day. If you are taking a krill oil supplement, be sure to factor in the amount of astaxanthin you are already receiving from krill and adjust the recommended dosing accordingly.

You need your eyes for a lifetime and they are most definitely worth protecting. Beyond being a window to your soul, you now know they are also an important indicator of your health. Take steps today to safeguard your vision. A great first step may be to schedule that eye exam you’ve been putting off! You won’t regret having your eyes checked by a professional or the peace of mind that comes with proactively taking control of your health.

Sources and References

• ¹ ABC News, April 11, 2012
• ^2, 11 Business Insider September 22, 2014
• ^3, 5, 8 Neurology February 28, 2018 [ePub ahead of publication]
• ^{4, 6, 7, 9, 10, 12, 13} CNN Health March 1, 2018
• ¹⁴ The Lupus Foundation of America July 15, 2013
• ¹⁵ National Multiple Sclerosis Society, Vision Problems
• ¹⁶ Healthline, What Causes Blindness?

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