context: They can help correct a lazy eye, delay glaucoma's onset, or moisten dry eyes. These days, eye drops can do more than ever before. Eye drops usually have saline as a base ingredient. They can keep your eyes wet and get the red out. Sometimes, they're medicine. You might get them for: Cataract surgery: Before this operation, you'll use eye drops to prevent infection, make your pupil larger, and numb the area. After the doctor removes your cloudy lens and replaces it with a man-made model, drops can lower the chances of infection and help you heal. Conjunctivitis ( pinkeye ): Drops can treat this infection or irritation of the conjunctiva, the clear membrane that lines your eyelid and covers your eye. If the cause is a bacterial or viral infection, you'll get antibiotic drops. If allergies or something else in the air like smoke or chemicals (your doctor will call this an environmental irritant) are to blame, the doctor may give you anti-inflammatory eye drops. Contact lens rewetting : If your eyes feel dry when you wear your contacts, drops can help. Choose a product that says it's made for use with contacts. Other drops could discolor your lenses or temporarily change their fit. Infected cornea (keratitis): Again, the type of drop you get depends on the cause. Contact lenses can lead to bacterial or parasitic infections. Some people use extended wear lenses too long. Others don't replace the lenses, solutions, and cases as prescribed. It can also happen if you leave them in while you swim. You'll probably get antibacterial eye drops for a minor problem. For a more severe infection, you might need fortified antibiotic drops or more extensive treatments -- maybe even surgery. Take your contacts out right away and call the eye doctor if you think your eyes are infected. Corneal transplant surgery: You'll get drops after this operation, in which the doctor replaces your diseased or scarred cornea with a clear one (usually from an eye bank). The drops help with healing and prevent rejection of the donor tissue. Dry eye: As you get older, your body makes fewer, lower-quality tears. You may have more than you used to -- these are called reflex tears. But they don't stick around long enough to get your eye wet. Other signs of dry eyes are: Sandy or scratchy feeling Burning or stinging Pain Redness Stringy discharge Heavy eyelids Changes in vision Over-the-counter artificial tears can help, but you should use them only during the day. Other treatments can help more severe cases. Eye allergies: Drops can help with symptoms like itchy eyes, tearing, redness, watery discharge, stinging, and burning. You might try artificial tears, which don't have medication, or drops that contain: Antihistamines: They provide short-term relief. Mast cell stabilizers: They're similar to antihistamines but give longer relief. Some eye drops have both antihistamines and mast cell stabilizers for quick and long-lived relief. Decongestants: You can find them (alone or with antihistamines) in many over-the-counter drops, including ones that reduce redness. Don't use them longer than 2 to 3 days. If you do, they can make your redness and swelling worse. Nonsteroidal anti-inflammatory drugs ( NSAIDs): They can help, but they might sting or burn a little when you put them in. Prescription corticosteroids: They can ease severe or chronic symptoms, but you'll use them for only a short time. If you have eye allergies and wear contacts, ask your eye doctor about eye drops to keep your lenses clear when you're exposed to an allergy trigger. Eye exams : During a complete eye exam, the eye doctor may use: Drops to dilate your pupils -- make them bigger so she can see inside your eye Drops to numb your eye while she checks for glaucoma Glaucoma: This condition is often associated with increased fluid pressure inside your eyes. It can cause serious optic nerve damage and vision loss if you don't treat it. In the early stages, eye drops can reduce the amount of fluid your eye makes and help more liquid drain from it. They may also prevent people with high eye pressure from getting glaucoma. If you have glaucoma, don't use eye drops with vasoconstrictors -- decongestants that make blood vessels in your eye smaller. That will boost your eye pressure. Herpes simplex eye infection: Early symptoms of this virus may include a painful sore on your eye surface or eyelid, and an inflamed cornea. Prompt treatment with antiviral eye drops or gel can help prevent damage. LASIK eye surgery: It can help if you're nearsighted, farsighted, or have astigmatism. You'll get eye drops before to numb your eye and prevent pain. After surgery, eye drops can help you heal and prevent infection. Lubrication and protection: Over-the-counter artificial tears are considered safe. But check with your doctor if: You're allergic to any type of preservative. You've ever had an unexpected or allergic reaction to the ingredients in artificial tears. Try several brands to find one that works best for you. Some over-the-counter products that ease allergy symptoms or get rid of red eyes contain a type of decongestant called a vasoconstrictor. They can cause "rebound" swelling and redness, which may lead to chronic eye redness. The redness may even get worse with continued use. Ask your eye doctor which eye drops are safest for you. It is not possible to become overly dependent on artificial tears without preservatives. Because these eye drops contain harmless moisturizers and no medication, they're very safe no matter how often they are used. Some eye drops contain benzalkonium chloride preservative, which can cause hypersensitivity reactions. Discuss this with your doctor whenever you use any eye drops frequently and for a long time, such as for treatment of glaucoma. Mostly yes, if it's just to wet the eyes or treat specific eye conditions. But there hasn't been a lot of research to figure out if medicated eye drops are safe and really work for kids. Ask your child's doctor to suggest a dosage, and follow her instructions exactly. Report any side effects right away. Eye drops can help kids with: Allergies. There are two types that treat symptoms: Artificial tears, which are safe and OK for children of all ages. Eye drops with antihistamines alone or antihistamines/mast cell stabilizers. They're OK for kids 3 and older. Lazy eye (amblyopia). This means one eye is stronger than the other. It happens most often to kids 6 or younger. Some doctors use medicated drops to blur the strong eye, so the weak one has to work harder. It's easier for kids than the usual treatment -- a patch over the strong eye. Nearsightedness (myopia) There is growing evidence that the use of atropine or dilute atropine drops in children at risk for developing nearsightedness can slow down the progression of nearsightedness. Are eye drops on the way out? Scientists have come up with a way to get tiny doses of medicine into your eye. These nanoparticles, as they're called, are so small that millions of them could fit onto an ant. You place the particles into your eye just once. They break down over time and release the medication as they dissolve. Possible future jobs for eye drops: They could replace eye shots for people with the wet form of age-related macular degeneration. Combined with a laser eye test, they could help diagnose Alzheimer's disease earlier than is possible now. All eye drops should be sterile when you use them. Check each bottle you buy to be sure the seal is intact. Don't let the applicator touch your eye's surface or anything else. This is key with preservative-free eye drops. If you use two or more different types, don't apply them together. Use one, wait 5 minutes, and use the other. Use them only as directed by your doctor or the label on the bottle. Throw them out when your doctor or the maker says to. Ask your doctor for dos and don'ts on how to use them.