Contact lenses: What to know before you buy
With contact lenses, you can get excellent vision correction and comfortable fit. If you decide to try contact lenses, find out the best type for your vision problem, lifestyle and budget.
Worldwide, about 135 million people with vision problems wear contact lenses — tiny discs of plastic placed on the surface of the eye — instead of glasses.
Wearing contact lenses isn't without risk, but proper selection and maintenance can help keep complications to a minimum.
Types of contact lenses
Contact lenses are made of many different types of plastic, but in general, they fall into two main groups: soft contact lenses and gas permeable contact lenses.
Soft contact lenses
These thin, gel-like lenses conform to the shape of your eye. They're more flexible than gas permeable contact lenses, so they're more comfortable and easier to get used to. Soft contact lenses tend to stay in place better than do gas permeable lenses, so they're a good choice if you participate in sports activities or otherwise have an active lifestyle.
Soft contact lenses come in single use, daily wear and extended wear varieties.
- Single use contact lenses. Some contact lenses are individually packaged for a single one-day use only. You put in a new pair every day, then remove and discard them before you go to sleep at night. Ordinarily, you don't need any special solutions to use these lenses, as an adequate amount of solution for one day of use is contained within the packaging. Single use contact lenses are the most expensive of the soft contact lens options.
- Daily wear contact lenses. These disposable contact lenses are designed to be used daily and may be reused from one to four weeks, depending on the manufacturer and design specifications. Lenses designed for four weeks of use tend to be somewhat stiffer than are those designed for seven-day use. Typically, you insert these lenses every morning and remove them every night. Proteins and micro-organisms collect on the surfaces of daily wear contact lenses, so you'll need to clean them every day and replace them on a regular schedule, according to the manufacturer's guidelines.
- Extended wear contact lenses. Designed for up to seven days of continuous wear, these contact lenses allow oxygen to reach your cornea even while you're sleeping. Most doctors, however, question the safety of wearing corrective contact lenses around the clock. Despite being made for prolonged wear, extended wear contacts block a certain amount of oxygen from your cornea — particularly when you're asleep. Overnight wear also promotes the buildup of micro-organisms on the lenses and is linked to an increase in the incidence of corneal complications, including infections.
Gas permeable contact lenses
Gas permeable contact lenses are more rigid and smaller in diameter than are soft contact lenses. One of their chief advantages is breathability: Your cornea needs oxygen for optimal health and function. Gas permeable lenses allow more oxygen to pass through them than do soft lenses, so corneal irritation is less likely. Their disadvantage is that they're initially less comfortable than soft lenses. Most people get used to them quickly, but if you stop wearing them for more than a few days, you'll have to readapt.
Gas permeable lenses can correct certain vision problems — such as refractive errors that require high spherical or cylindrical powers — more accurately than can soft lenses. They're also more durable and easier to care for.
If your prescription doesn't change and you take care of your gas permeable lenses, you can go two or three years without replacing them.
Hybrid contact lenses
Hybrid contact lenses feature a gas permeable center surrounded by a soft outer ring. Hybrid contact lenses may be an option for people needing vision correction for problems such as astigmatism, keratoconus or presbyopia. These lenses offer the combined benefits of optimal visual acuity associated with gas permeable contact lenses and greater comfort associated with soft contact lenses. If you require gas permeable lenses but can't wear them comfortably, a hybrid lens may be the answer.
Pros and cons of soft vs. gas permeable contact lenses
How do you choose between soft contact lenses and rigid gas permeable contact lenses? Here's a look at the advantages and disadvantages of each.
| Contact lens type | Advantages | Disadvantages |
|---|---|---|
|
Soft |
Flexible, more comfortable Extended wear and disposable options available Shorter adjustment period Stay in place better, even with vigorous physical activity |
Less durable Require more frequent replacement Not as effective in correcting some vision problems, such as high degrees of astigmatism |
|
Gas permeable |
Optimal vision correction for many conditions More durable Less frequent replacement needed Greater oxygen permeability; better for eye health |
Less comfortable initially; require adjustment period Readjustment necessary any time you stop wearing them for an extended period May slip off the center of your eye more easily; could lead to discomfort and blurred vision |
Specialized contact lenses
Both soft and gas permeable contact lenses have become more versatile in recent years, so more people are able to wear contacts for vision problems once correctable only with glasses. Specialized contact lenses also play a role in treating some eye conditions other than impaired vision.
-
Contact lenses to correct presbyopia. Presbyopia is the gradual loss of close-up vision. Contact lens options to correct presbyopia include bifocal lenses, monovision and modified monovision. Bifocal contact lenses feature two prescriptions on one lens: one to correct distance vision and the other to correct near vision. Bifocal contact lenses are available in daily wear soft and gas permeable materials.
Monovision involves using a contact lens with your reading prescription in one eye and a contact lens with the distance prescription in the other eye. Modified monovision entails wearing a bifocal or multifocal contact lens in one eye and a single-vision lens in the other eye. For instance, you may have a lens for distance correction in your dominant eye and a bifocal lens in the other eye. Both eyes can be used for distance viewing, but only one eye for reading. Monovision requires some getting used to, and not everyone will find this type of vision correction comfortable.
- Scleral contact lenses. Scleral contact lenses are made of gas permeable materials. They're larger than standard gas permeable or soft contact lenses, and are designed to rest on the less sensitive white part of your eye (sclera), not your cornea. Scleral contact lenses provide space for a protective layer of saline between the lens and your eye. This allows for better comfort and better vision for people who can't wear glasses or regular contact lenses due to corneal inflammation or very irregular corneas or ocular surface problems — such as might occur with severe astigmatism, keratoconus, corneal inflammation, Stevens-Johnson syndrome or after corneal surgery.
Avoiding eye infections
Wearing contact lenses increases your risk of corneal infection. Some of the added risk is unavoidable: All types of contact lenses reduce the amount of oxygen that reaches your cornea — the clear tissue that lies over the pupil and iris — and less oxygen can promote infection.
This reduction in corneal oxygen makes proper cleaning and disinfection all the more important. Here are some tips:
- Wash, rinse and dry your hands thoroughly before handling your contacts.
- Use multipurpose contact lens solutions with caution. While combination cleaning-disinfectant-storage solutions are convenient, two brands have been withdrawn from the market in recent years because they've been linked to serious eye infections. Do not use any solutions that have become discolored; this might mean that the product is out of date or contaminated. Gently rubbing the lenses during cleaning enhances the cleaning performance of the solutions.
- Choose daily wear contacts, and take them out before you go to sleep. Infections are more common with extended wear contacts, worn continuously, than with daily wear contacts.
- Follow your eye-care professional's instructions for taking care of your lenses. Use only sterile products that are commercially prepared specifically for contact lens care, and make sure you use lens-care products formulated for the type of lenses you wear.
- Replace your contact lenses as recommended. If one or both lenses bother you before you're due to replace them, get them checked or try a new set — if you have a supply.
- Replace your contact lens case every three to six months. Discard the solution in the contact lens case each time the lenses are disinfected. Don't "top off" old solution that's already in the case.
- Wear contact lenses only to correct your vision. Costume contact lenses aren't regulated by the Food and Drug Administration and may cause serious eye injury or even blindness.
Getting the right fit
If you decide you want contact lenses, have a thorough eye examination and fitting by an experienced professional. Follow-up exams are important to monitor any changes to your vision and to update your prescription. If you're a regular contact lens wearer, see your doctor annually for an eye exam and a contact lens evaluation — more often if you have any problems.
Reprints and permissions
Home 
