If the eyes are the mirrors of the soul, bloodshot eyes are the mirrors of your health, letting you know that something’s going on either with your eyes themselves or in another part of your body.

By Claire Gillespie and Kristin Canning
October 09, 2020
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An unexpected talking point from the first vice presidential debate on Wednesday night was Vice President Mike Pence's left eye, which was noticeably red and blurry. Viewers got a good look at it every time Pence turned to his right to address his Democratic rival, Senator Kamala Harris—and the internet went wild theorizing the possible causes. A White House official told Politico on Thursday that Pence simply had a burst blood vessel.

So many conditions can cause one or both of your eyes to take on a reddish hue and it’s not always easy to figure out what’s causing the redness—and what you should do about it.

“Usually the eyes turn red because the blood vessels on the surface of the eye get dilated or inflamed,” explains Jessica Lee, MD, assistant professor of vitreoretinal surgery, department of ophthalmology at the New York Eye and Ear Infirmary of Mount Sinai. “And there are a multitude of reasons that can happen.”

Some of these reasons are simple and have an easy fix, while others are more serious; red, inflamed, and/or itchy eyes could be the first sign of a condition that may have a real impact on your vision. We asked the experts to explain all the things that could cause red eyes, so you can better determine why you’re sporting the bloodshot look and how to treat it.

COVID-19

Naturally, COVID-19 is at the front of everyone's minds at the moment, and with the virus currently sweeping through the White House, social media users were quick to suggest Pence's red eye was a sign of infection. Incidentally, his team said he tested negative for COVID-19.

But the Internet was onto something—COVID-19 can cause pink eye. In June, a case study from the University of Alberta, published in the Canadian Journal of Ophthalmology, said conjunctivitis can be a primary symptom of COVID-19. The subject of the study was a 29-year-old woman with severe conjunctivitis and minimal respiratory symptoms who tested positive for COVID-19.

The American Academy of Ophthalmology has also warned that the coronavirus can cause conjunctivitis. But the Centers for Disease Control and Prevention (CDC) doesn't include pink eye on its list of known COVID-19 symptoms.

"Red eye isn't a common manifestation of COVID-19, but it has been reported," Kathryn A. Colby, MD, chair of the department of ophthalmology at NYU Langone Health, tells Health.

Allergies

Allergic conjunctivitis is a reaction to something an individual is allergic to, Dr Colby says. It's common in people with seasonal allergies (hay fever) and tends to occur when pollen counts are high. Someone with different types of allergies, such as pet dander or dust, may experience pink eye when they spend time with a dog or clean their home. Allergens produce histamines in the body, which then cause inflammation. Unlike viral and bacterial conjunctivitis, allergic conjunctivitis isn't contagious.

The redness will start to go away once you are no longer exposed to the allergen, but that can take a while, depending on the severity of your allergy. To speed things up, splash your eyes with water or use a cool compress on them. Over-the-counter eyedrops designed to counter allergies can help, as can antihistamine meds. Try to figure out what caused your reaction and avoid coming into contact with it again, Dr. Lee says.

Alcohol

If you've ever had one too many drinks and noticed at the time or the next day that your eyes sported bright red spider veins in them, then you've experienced alcohol's effect on the eyes. Here's what happens: Alcohol causes the tiny blood vessels on the eyes to dilate, so more blood flows through them. The more you drink, the more visible and red they appear against the whites of your eyes, says Dr. Lee.

Over-the-counter eye drops can help lessen the redness, and as the alcohol leaves your system in the hours after your drinking binge, the blood vessels will return to normal.

Bacterial infection

Pink eye can also be caused by a bacterial infection, Dr. Colby says—often the same type of bacteria that cause strep throat and staph infections, such as Streptococcus and Staphylococcus. As with viral conjunctivitis (see below), optimum hygiene is important to stop the pink eye spreading to someone else. Wash your hands often with soap and water for at least 20 seconds and avoid touching or rubbing your eyes, and sharing makeup, contact lenses, and glasses.

Common cold/upper respiratory tract infection

A more common cause of conjunctivitis is the common cold (a nose or throat infection), Dr. Colby says. Many types of virus can cause a cold, but the most common are rhinoviruses, per the CDC. If you have a runny nose, you'll probably be doing lots of wiping, and if you then rub your eyes, the virus can spread.

The best way to avoid pink eye when you have a cold—or someone else in your home does—is to be scrupulous about hand-washing. Conjunctivitis can also be caused by an upper respiratory tract infection if the virus spreads via the body's mucous membranes from the lungs to the throat, nose, tear ducts, and conjunctiva (the loose connective tissue that covers the surface of the eyeball). Pink eye could also be caused by exposure to someone else with an upper respiratory tract infection when they cough or sneeze.

Contact lens issues

Contact lenses can prevent enough oxygen from reaching your eyes, leaving them bloodshot and irritated, says Dr. Lee. “If the lenses are worn too long or worn while sleeping, they can cause redness, infections, and in worst-case situations corneal ulcers.” Futhermore, a condition called CLARE (contact lens-induced acute red eye) is a reaction to the toxins that normal bacteria create in the eyes. Usually, these toxins are simply flushed out of the eye by blinking, but they can attach to the surface of a contact lens, build up and lead to eye redness. According to the April 2015 issue of Review of Cornea & Contact Lenses, CLARE is most common in people who sleep in their contact lenses overnight.

Steer clear of these issues by following the lens care directions closely, cleansing them properly, practicing good contact lens hygiene, and taking them out before you fall asleep. In the meantime, eye drops can ease the redness and soothe irritation.

Dry eye

Glands in the eyes produce tears constantly—not only when we cry. And when tears evaporate too quickly, or not enough tears are produced, it can lead to inflammation in the eye, Dr. Colby says. Sometimes, dry eye (also known as dry eye syndrome) can actually be caused by inflammation along the eyelids, which is called blepharitis. "There are other reasons for dry eye," Dr. Colby adds. "Sometimes it is due to an environmental issue—like too much device screen time or a long airplane flight. Less commonly, dry eye can be a sequela of a systemic disease like rheumatoid arthritis."

Glaucoma

Glaucoma is actually a series of diseases that damage the optic nerve (the nerve that connects the retina of the eye to the brain), often when too much pressure is put on the eye due to fluid buildup. One of the first signs of one type of glaucoma, called acute angle-closure glaucoma, is redness, according to the Mayo Clinic. Other signs include blurred vision, seeing halos around lights, and pain in the eyes. This condition is uncommon, but develops quickly and demands immediate medical attention.

Though glaucoma is more common among older adults, anyone of any age can develop one of the types of the disease. Getting regular eye exams can catch it early and slow down vision loss with the help of medication.

Pink Eye

Pink eye is the non-medical term for conjunctivitis—a bacterial, viral, or allergy-induced infection that leaves one or both eyes bright red, swollen, teary and itchy, says Jessica Lee, MD, assistant professor of vitreoretinal surgery, department of ophthalmology at the New York Eye and Ear Infirmary of Mount Sinai. It's easily spread, unfortunately, and though it rarely becomes serious, a bout of conjunctivitis can keep you away from work for several days and turn your eyes into goopy, pinkish-red messes.

The condition doesn't necessarily require a doctor's visit; applying a cold compress can help ease the redness and make your eyes feel better. But if you're not sure if what you have is conjunctivitis, or the infection doesn't go away in a few days, check in with your MD. The type you have will determine how and if your doctor can treat it—for example, if it's bacterial, antibiotic eyedrops can help.

If you have either viral or bacterial conjunctivitis, practice good hand hygiene to keep it from spreading to other people in your household. Sharing towels or makeup, or just touching your eyes and then making contact with another person, can transmit it.

Stye

A stye is a small red bump that forms on your eyelid or bottom edge of your eye after an oil gland there becomes plugged up. You could have just one or several, and each will resemble a pimple or boil. One of the first signs is redness, along with swelling and sensitivity. They're caused by bacteria and almost everyone will have them at some point.

Luckily a stye doesn't affect your vision. But it isn't exactly pretty, and getting rid of it generally involves waiting it out and letting it go away on its own in several days. Like all pimples, touching it can make it worse. And of course, don't try to pop it; that too can worsen the infection. If you get styes frequently, see your ophthalmologist, who may prescribe an antibiotic ointment.

Subconjunctival hemorrhage

A subconjunctival hemorrhage happens when a blood vessel just under the eye surface breaks, and blood gets trapped and forms a bright red patch in the white of your eye. It's a common injury and though the hemorrhage looks serious, it won't likely affect vision or cause any pain, discharge, or swelling.

A subconjuctival hemorrhage can be brought on when you overexert yourself, say at the gym or by lifting something heavy, or even by a strong sneeze or cough. Even throwing up can trigger hemorrhaging, as can direct trauma to your eye. The red patch usually fades over a few weeks.

Too little sleep

Tired eyes tend to be bloodshot eyes. That's because a lack of sleep can decrease the amount of oxygen that reaches your eyes, which in turn causes blood vessels in them to dilate and appear red.

Another factor that leads to redness comes into play as well. “If your eyes are kept open for a long time because of lack of sleep, it prevents the cornea (the surface of your eye) from being well lubricated, and this can cause dryness and redness,” says Dr. Lee. “The best way to calm them would be to get more sleep, and use artificial tears and cool compresses to ease the discomfort.”

How to treat eye redness

Dr. Colby says specific treatment of conjunctivitis or eye redness depends on the cause. Artificial tears can help lubricate the eye and wash out any irritants, while antibiotics and antivirals are often used to treat infectious conjunctivitis. Antihistamine or mast cell stabilizer eye drops are common treatments for allergic conjunctivitis. "If someone is experiencing severe symptoms, such as loss of vision or eye pain, in association with a red eye, they should make an appointment for an eye exam," Dr. Colby says.

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