Shingles, herpes, chlamydia, and more unexpected health problems can plague your peepers.

Karen Pallarito
May 23, 2018

Those lovely orbs of yours reveal more about your overall health than you might suspect. They offer a window on all sorts of infections, chronic diseases, and even cancers.

Did you know that swelling in the eye could be a complication of a gut issue? Or that blurry vision is sometimes a sign that your blood sugar is out of whack?

Some conditions directly infect the eye through contact with body fluids, for example, while others travel systemically to the eyes via the blood or nerves.

If you rarely make time for a thorough, dilated eye exam, you’re missing out on a crucial opportunity to save your vision and stave off potentially serious illnesses.

“The quicker we catch these things that may not be just isolated to the eye, the better the patient’s health can be,” says Laurie Barber, MD, a clinical spokesperson for the American Academy of Ophthalmology (AAO).

Here are a few of the ordinary and odd ailments that can show up in your eyes.

Melanoma

Performing a full-body check for moles that morph in size, shape, color, and texture can help you catch this aggressive skin cancer while it’s treatable. But don’t forget to have your eyes examined, too.

Melanoma can start in the eyes as a primary cancer or spread to the eyes as a secondary cancer that originated in another part of the body.

While it can invade any part of the eye, it’s often found in the choroid, the layer of blood vessels and tissue between the white of the eye and the retina in the back of the eye. Eye melanoma can cause vision changes, but often people have no symptoms until the cancer becomes more advanced.

Primary melanoma is the most common eye cancer, but you won’t find it by looking in the mirror, says Dr. Barber, also an ophthalmologist with Little Rock Eye Clinic. You need a dilated eye exam.

RELATED: What Is Ocular Melanoma?

Inflammatory bowel disease

If you have gut issues, definitely go for an annual eye exam. About 10% of people with inflammatory bowel disease (IBD) experience eye problems, according to the Crohn’s and Colitis Foundation.

Uveitis, or inflammation of the middle layer of the eye wall, is a common IBD complication. It can cause pain, blurred vision, light sensitivity, and eye redness.

Some people with Crohn’s disease develop keratopathy, a disease of the cornea.

Herpes

The herpes simplex virus is better known for causing cold sores on your lips and blistery bumps on your genitals. But it can also cause an eye infection.

Initially, the virus enters the eye if you touch an open sore (your own or someone else’s) and then touch your eye. Once the virus is in your eye, it can live there quietly until it’s reactivated by some trigger, like sun exposure, stress, or surgery.

Herpetic lesions of the eye or eyelids are usually painful, Dr. Barber notes. If herpes infects the cornea, you may have severe pain, eye redness, eyelid swelling, and decreased vision. The virus can inflame and scar the retina or cause it to become separated from the back of the eye, which can cause blindness, she says.

RELATED: 8 Reasons Your Eyes Are Red–and How to Treat Them

Other sexually transmitted diseases

Reported cases of chlamydia, syphilis, and gonorrhea are on the rise, and each of these STDs can get in your eyes. All the more reason to practice safe sex!

You can get gonorrhea or chlamydia in your eyes through direct contact with body fluids. Each can give you a mean case of pink eye.

Syphilis, by contrast, travels through the bloodstream, and “one of the places it can disseminate is the eye,” says Amesh Adalja, MD, spokesperson for the Infectious Disease Society of America and senior scholar at the Johns Hopkins Center for Health Security in Baltimore.

Syphilis can cause eye inflammation, pain, and vision problems, according to the AAO.

Toxoplasmosis

A tiny parasite causes this brain and eye infection. You get it by consuming undercooked, contaminated meat or handling cat feces and then touching your hand to your mouth.

Many people never have symptoms because their immune systems fight off the infection.

“Nothing really happens until maybe they get immunosuppressed, and then it can reactivate,” explains Dr. Adalja, also an infectious disease physician.

People with HIV or cancer, for example, and infants born to mothers who are infected during pregnancy are at greater risk of developing vision problems from toxoplasmosis.

Zika virus

Most people with this mosquito-borne illness have no symptoms at all. If they do, they might have very mild fever, rash, headache, joint pain, and muscle pain–and watery, red eyes.

“The virus is transmitted into the bloodstream, and it disseminates to multiple different organs, including the eye,” Dr. Adalja says.

You don’t have to be bitten by a mosquito to get Zika. It can pass from an infected person to a healthy person though sex or possibly a blood transfusion. Zika can cause severe birth defects, including vision problems, when it passes from a pregnant woman to a fetus.

RELATED: Everything You Must Know About Mosquitoes This Summer

Diabetes

Uncontrolled diabetes can harm your heart, blood vessels, nerves, kidneys, skin, brain, and, yes, your eyes.

Diabetic retinopathy, for example, damages delicate blood vessels in the back of the eye. It may cause no eye symptoms initially but eventually may produce “floaters” in your field of vision or cause blurry vision. It’s the leading cause of blindness in U.S. adults, according to the Centers for Disease Control and Prevention.

“I have diagnosed more than a handful of patients with diabetes just from their eye findings, and they didn’t know they had it,” Dr. Barber says.

RELATED: 7 Signs You Could Have Type 1 Diabetes

Kidney disease

Weird as it sounds, people with chronic kidney disease are at increased risk of developing vision-impairing eye diseases.

The reason? The eyes and kidneys share common risk factors, including diabetes and hypertension, as well as common disease pathways, such as inflammation and narrowing and hardening of the arteries.

Dr. Barber recalls examining a 17-year-old patient with severe “nicking changes” in her eyes. (In other words, the main artery supplying blood to the retina “looks like it takes a chunk out of the vein,” she explains.) Turns out her young patient had renal artery stenosis, or narrowing of the arteries that supply blood to the kidneys.

Stroke

Ischemic stroke, the most common type of stroke, is caused by a blood clot in the brain. But did you know you can also get a stroke in your eye?

This type of stroke occurs when a blood clot or a clump of fatty plaque clogs an artery in your eye, choking off the blood supply to the retina.

Eye stroke, also called retinal artery occlusion, can cause sudden or progressive vision loss, and it’s painless, Dr. Barber says. In some cases, the vision loss is permanent.

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Shingles

If you had chickenpox as a kid, you have the varicella zoster virus inside your body. As an older adult, it can recur, usually as a painful rash called shingles, which wraps around the torso.

“It’s not anything you’ve done wrong. It’s just a reactivation of the virus that’s kind of sitting there waiting to pop out,” Dr. Barber explains.

Sometimes, when the virus invades a nerve near the eye, it can cause eyelid swelling, eye redness, burning, and eventually severe damage that can lead to vision loss, called herpes zoster ophthalmicus. If you have a shingles rash around your eye, see your eye doctor.