You could have an infection.

You could have an eye infection: Do you wear contact lenses instead of glasses? Watch out for white spots on your cornea (that clear layer over the front of your eyeball). This is "quite common among people who wear contact lenses," Dr. Herz says, and can be a sign of a corneal infection.

PHOTO: BIOPHOTO ASSOCIATES

You're too stressed.

You're too stressed: Stress can manifest in many ways, one of which is an eye twitch. It's more annoying than concerning, but it can be a sign you need to get some more rest and manage your stress levels a bit more, Herz says.

PHOTO: WIN-Initiative

You could have diabetes.

You could have diabetes: Blurred vision usually means you need glasses — but you should have your eyes checked no matter what. Not only can blurred vision signal a medical problem with the eye itself (like cataracts or macular degeneration), it can also be a sign of a more serious illness like diabetes. In fact, an August 2014 study found that 73 percent of diabetic patients sampled reported blurred vision. Even without trouble seeing, your ophthalmologist may be able to detect diabetes during an eye exam based on irregularities in your retina.

PHOTO: N-Photo Magazine / Contributor

Your cholesterol is too high.

Your cholesterol is too high: If you notice a white ring forming around your corneal arcus (that's medical speak for your iris), it might be time to visit your ophthalmologist as well as your GP for a check-up. While this particular color change is most commonly a sign of aging, Herz says it can also be an indication of high cholesterol and triglycerides — which might mean an increased risk of heart attack or stroke.

PHOTO: WoodenDinosaur

Your blood pressure is too high.

Your blood pressure is too high: In addition to upping your risk for heart disease and strokes, untreated high blood pressure can also damage the blood vessels in your retina, known as hypertensive retinopathy. You can't see the effects in the mirror, but your doc will be able to spot the damage during your eye exam — even more reason to stick to your annual screenings, considering tipping you off to high blood pressure could actually save your life.

PHOTO: Ralph Jr

You have allergies.

You have allergies: If your eyes are super dry and the skin around them is looking a little worn, you might be unconsciously rubbing your eyes too often. "Rubbing your eye hard or often can cause your eyelid to become looser, more relaxed and even saggy," Herz warns. "If the eyelid sags away from eye, it not only causes wrinkles, but also allows increased exposure to air and can make the eye become overly dry." One of the most common culprits of itchy eyes: seasonal allergies.

PHOTO: drbimages

Your retina could be in danger.

Your retina could be in danger: You know those little specks that move around your field of vision sometimes? They're called eye floaters and, while they're relatively common, they also shouldn't be dismissed. Herz warns that a sudden increase in the number of floaters you see could be a sign of a retinal tear or detachment (yikes!).

PHOTO: primeimages

You need more zzzs.

You need more sleep: If you notice that your eyes are puffy and red, don't assume you have an infection. It might just be a sign that you're tired. "In addition to twitching, lack of sleep can make the eyes more irritated and red," Herz explains.

PHOTO: John Rensten

You're getting too much sun.

You're getting too much sun: Some people develop a yellowish patch or bump on the whites to the side of their iris, called a pinguecula. "A small percentage of these are pre-cancerous, but usually they are not," Herz says.

What causes them? "They are most often seen in people who spend a lot of time in the sun and are similar to a callus on the skin," she adds. But a December 2013 study looked at ultraviolet light's effects on the eye and found that wearing specific lenses may protect your peepers from sun damage, so talk to your ophthalmologist if you start seeing the patches.

PHOTO: apomares

You could have jaundice.

You could have jaundice: If the whites of your eyes are yellowing like old paper, it should come as no surprise that this is definitely a warning sign something is wrong in your body.

The biggest contenders for culprit? Jaundice, a condition that occurs when there's too much bilirubin — a yellow compound formed from the breakdown of red blood cells — in your blood. If your liver can't filter the cells, bilirubin builds up and can cause your eyes and skin to turn yellow. It's pretty rare in adults (sometimes babies are born with jaundice), but much of the time it's due to an infection like hepatitis, alcohol-related liver disease, or something blocking your bile ducts like gallstones or cancer.

PHOTO: Oktay Ortakcioglu

You're spending too much time on the computer.

You're spending too much time on the computer: As much as we love Netflix, too much screen time could be causing your eyes to strain and tear up. "Although it sounds ironic for tearing to be a symptom of dry eye, it's the eye's response as it tries to make up for being too dry," Herz explains. "This is very common among people who spend much of their day looking at a computer screen or television screen."

PHOTO: Tim Flach

You're straining your eyes.

You're straining your eyes: Broken blood vessels may look alarming, but for the most part they're simply an indication that your eyes are working overtime. "It most likely is caused by coughing or straining," Herz explains. "Even though it looks blood-red and terrible, it is harmless and not indicative of any eye disease."

PHOTO: DawnPoland