context: Contact lenses have come a long way and offer some exciting options. You can bat a pair of baby blues one day, then flash golden tiger eyes the next. You can even toss disposable lenses in the trash each night. For people with vision problems, contacts remain an effective, almost invisible tool. The thin plastic lenses fit over your cornea -- the clear, front part of your eye -- to correct vision problems including nearsightedness, farsightedness, and astigmatism. You can wear contacts even if you have presbyopia and need bifocals. Talk to your eye doctor about the best type of lenses for you. Get regular eye exams to keep your peepers healthy and make sure your prescription stays up to date. They're made from a special type of plastic mixed with water. The water content lets oxygen pass through the lens to your cornea. That makes the lenses more comfortable, lessens dry eyes, and helps keep your cornea healthy. If it doesn't get enough oxygen, it can swell, get cloudy, and cause blurry vision or other, more serious problems. Pros. Many soft lenses are disposable, so you can throw them away after using them for a short time. Having a fresh pair of soft contacts means less chance of infection, less cleaning, and more comfort. While soft contact lenses are commonly throwaways, there are some soft lenses that aren't aren't. Depending on what yo need for your eyes, you may wear the same pair for about a year and clean them each night. These are typically more custom-designed contact lenses. Compared with rigid gas-permeable lenses, the other main type of contacts, soft lenses feel better when you first put them in. As a bonus, many soft lenses provide UV protection. Cons. Soft contact lens material can absorb particles, chemicals, bacteria, and mold more easily than both hard and rigid gas-permeable lenses. They soak up all kinds of things that can irritate your eyes -- smoke and sprays in the air and lotion or soap on your hands. Soft contacts are also more fragile. They can rip or tear more easily than hard or gas-permeable lenses. Varieties. New types of soft lenses come to market as new technologies develop. Daily disposables are soft contacts that you wear only for a day and then throw away. That means you don't have to clean them regularly or risk dry eyes and irritation from contact solutions. If you have allergies, they may be the best choice for you. Silicone-based materials create an extremely breathable lens that lets plenty of oxygen pass through to your cornea. They also keep deposits from building up. That means less irritation from dry eyes. Some silicone contacts are FDA-approved for extended wear, so you can use them for up to 30 days. But many eye doctors say to remove any type of contact lens at bedtime. Why? Your cornea gets less oxygen when you sleep in contacts, so the risk of serious complications is higher. Silicone lenses aren't for everyone, so talk with your eye care professional if you're interested in them. They're hip, they're fun, and colored contacts can even be practical. Visibility tint lenses have a tiny bit of color so you can find your lens if you drop it. It isn't enough to affect the color of your eyes. Enhancement tint lenses play up your natural eye color. They're slightly darker than a visibility tint. Color tint lenses are darker, opaque, and change the color of your eyes. Specialty colors include amethyst, violet, and green. Remember, colored contacts are a medical device just like clear lenses. Get them from your eye doctor and nowhere else. Don't share them with anyone. Clean and care for them just as you would any prescription lenses. As the name suggests, these are stiffer than soft contacts. They're made from silicone, and they're designed to let oxygen pass through to your cornea. Pros. You might see better than you do with soft lenses. They correct substantial astigmatism. They're easy to take care of and durable. Cons. At first. the lenses don't feel as comfortable as soft contacts. It takes longer to get used to them, so you need to wear them every day. As you age, the lens in your eye loses the ability to focus from far to near -- a condition called presbyopia. You'll know you have it when it's hard to read up close. If you have trouble with both near and far vision, bifocal lenses can help. They have both your distance prescription and near prescription in one lens. They come in soft and gas-permeable options. You need a professional fitting and evaluation to know which bifocal design is best for your needs. You won't have the same prescription in both eyes. One will have a contact for distance vision, and the other will be for seeing up close. This can take a while to get used to. Each eye works on its own. That makes it harder for them to work together. You might have problems with depth perception. That can make it hard to drive. You might have to adjust your gaze more often to allow one eye or the other to see properly. Another monovision option: Wear a bifocal lens in one eye, and a single-vision lens in the other. This makes driving easier. One more option: Get your contact prescription for distance vision. Wear reading glasses over your contacts when you need to see up close. If you have astigmatism and want to wear contacts, you'll need a toric lens. They're made from the same material as other contacts but work with your eyeball, which isn't completely round. They come in soft or rigid gas-permeable forms, extended wear, daily disposable, and even in colored lenses. Like bifocal lenses in a pair of glasses, toric lenses have two powers in one lens: one that corrects your astigmatism, and another for nearsightedness or farsightedness. If you're mildly nearsighted, your eye doctor may suggest orthokeratology, or ortho-k for short. She'll use a special contact lens to reshape your cornea -- and improve your vision. But the results only last while you have the contact in. This procedure isn't widely used, because laser vision correction offers the same result in less time and is permanent. Laser surgery is now OK for professionals -- like members of the military or airline pilots -- whose jobs didn't allow them to have it in the past. If you can't have laser surgery, ask your eye care professional if ortho-k could work for you.