Red or Bloodshot

Tiny blood vessels in your eye may expand or burst when they get irritated or infected. It could also be a sign of allergies or dryness. It's pretty common and often goes away without treatment. An injury, glaucoma, and cuts, scratches, and sores on your cornea could be more serious. Check with your eye doctor if your eye hurts or doesn't improve in a day or two, or if you have trouble seeing.

Burning or Stinging

It's often a sign of tired or irritated eyes, possibly from hay fever, dust, or smoke. It may also be a sign of blepharitis, a buildup of bacteria that causes dandruff-like flakes on your eyelids, or dry eye, when your eyes don't make good-quality tears or enough of them. A more serious issue is an inflamed cornea, also known as keratitis.

Crust

When tears and oils dry, they can leave a sticky crust on your lids or lashes. A small amount when you wake up is normal, but you may need to see a doctor if you have more than usual, it's yellow or greenish, or you have other symptoms, too. Pinkeye is contagious. Blocked tear ducts can lead to the buildup of tears and fluids on your eyes. Blepharitis can cause problems with your oil glands.

Dry or Itchy

Irritated eyes are often caused by allergies, medications, wearing contact lenses, aging, diseases like arthritis, and eyestrain from computer use. Eye drops may help. Look for ones that moisturize. Don't use drops for redness. Another way to get relief is to put a cold compress on your eyes. You should never rub an itchy eye. If it won't go away, see a doctor who can help you treat the cause, not just the symptom.

Puffy Eyes

It's often easy to figure out what's causing this -- from allergies, pinkeye, or another infection or inflammation to bumps on your eyelids, sores on your cornea, or a black eye. In rare cases, it may be thyroid problems. Often the swelling goes away on its own. If it lasts longer than 24 hours or if you have trouble with your vision, call your doctor right away.

Watery

Tears are a good thing. They keep your eyes moist, and they help wash out things that don't belong. When you have watery eyes, that means either your tears are working overtime or they can't drain away normally. It may be something that will clear up, or it could be an infection, a cut or scrape, or blocked tear ducts. You should definitely see a doctor if your eyes hurt, you have trouble seeing, or it feels like something's in your eye.