There are many ways to correct vision. You can choose from among a half dozen types of eyeglass lenses and thousands of frames. Contact lenses come in daily or extended wear and can even change your eye color. Laser surgery may eliminate the need for any corrective eyewear.
Types of Impaired Vision
Vision described as 20/20 is perfect. If your sight cannot be corrected to at least 20/200, you are considered legally blind. Most vision impairments are called refractive errors, which include the following diagnoses:
- Myopia: nearsightedness. Faraway objects are blurry.
- Hyperopia: farsightedness. Close objects are difficult to see.
- Astigmatism: misshapen cornea, which hinders focus. Usually paired with myopia or hyperopia.
- Presbyopia: gradual, age-related loss of focus.
Vision Correction with Eyeglasses
Eyeglass lenses come in various shapes to correct different conditions. Concave lenses treat nearsightedness, convex lenses remedy farsightedness and a lens shaped like a cylinder betters astigmatism. People with presbyopia need multifocal lenses -- which include two or more prescriptions -- such as bifocals, trifocals or progressive lenses.
Some lenses are still made of glass and standard plastic, and there are four types of improved plastic lenses.
- Hi-Index: Thinner, lighter lenses made of plastic. Cost is greater, but make high-prescription glasses more attractive.
- Polycarbonate: Plastic lenses that resist impact and provide ultraviolet protection. Ideal for athletes, children and for use in safety glasses.
- Trivex: As impact-resistant as polycarbonate, but thicker. Also good for kids, sports and safety use. Its rigidity makes it a good selection for rimless or drill mount frames.
- Aspheric: Lighter weight, can correct with less of a curve, preventing the eyes from appearing magnified when a strong prescription is used.
Coatings and treatments can be applied to make lenses anti-reflective, scratch-resistant or protect eyes from UV sunrays.
Vision Correction with Contact Lenses
There are two basic types of contact lenses:
- Soft contact lenses are flexible and comfortable, and come in three types. Single-use soft contacts, daily wear and extended wear -- which can be kept in for up to seven days.
- Gas permeable contact lenses are smaller, less flexible and take more time to get used to. They allow the cornea to breathe better than soft lenses, lessening the chances for corneal irritation. Gas permeable lenses are better at correcting certain vision problems and they last longer -- up to two or three years with regular care.
Some people with presbyopia may need bifocals, which include corrections for distance and near vision. Employing monovision -- a close-up prescription lens in one eye, distance prescription in the other – is helpful for others.
Toric lenses are designed to correct both astigmatism and myopia or hyperopia using a single lens in each eye. People with severe astigmatism or problems with their corneas may benefit from scleral contact lenses, which are larger so that they make contact with the white part of the eye and not the cornea.
Preventing Infection Caused by Contact Lenses
All contact lens wearers must be very careful to avoid infection:
- Wash hands before touching lenses
- Clean and disinfect as directed
- Don’t re-use solutions
- Store contacts in a clean, dry case
- Remove them before swimming or bathing
- Replace them regularly
Failing to follow these steps can lead to serious consequences including irritation, infections, corneal ulcers and blindness.
Contact lenses are generally more expensive than eyeglasses, partly because of the solutions required for cleaning and storing. People with dry eyes or overly teary eyes can usually not wear contacts.
Vision Correction Surgeries
Laser eye surgery permanently alters the shape of the cornea to correct nearsightedness, farsightedness or astigmatism. Two types are well known.
- Lasik: Lasik stands for Laser-Assisted In Situ Keratomileusis. During laser surgery, patients are awake (their eyes are numbed), and can resume most normal activities after one day. A steel blade is used to create a corneal flap; a laser is used for the actual correction. It may take up to six months to achieve the full effect. While laser surgery will restore 20/20 to 20/40 vision in most people, it may not completely remove the need for corrective lenses.
- Intralasik: Intralasik employs only lasers during the surgery. People with thin or flat corneas who might not qualify for lasik can often undergo intralasik.
- Photorefractive Keratectomy is another option for those with thin corneas.
The cost of lasik varies from state to state, but can run from $499 to $2,500 for each eye. Intralasik costs about $500 more per eye. These procedures are not performed on certain candidates such as those who are under 18, pregnant, nursing, taking specific drugs, in poor health, or people with dry eyes or unstable vision.
- Radial keratotomy is similar to laser surgery except it requires actual instruments throughout the procedure. It corrects only nearsightedness.
Two other surgeries can help patients achieve good vision:
- Conductive Keratoplasty tightens corneal collagen to restore good vision to those who use glasses for reading or close work only.
- Multifocal Intraocular Lens Implant is a higher-risk procedure that implants artificial lenses for better close-up and distant vision.
Related Vision Correction Resources
About.com Healing: Alternatives to Wearing Eyeglasses [1] About.com Health Topics A to Z: LASIK Eye Surgery [2] About.com Vision Avoiding Infection [3] About.com Vision Contacts [4] About.com Vision Contacts for Astigmatism [5] About.com Vision Contacts Risks [6] About.com Vision Contacts Types [7] About.com Vision Cross Eyes [8] About.com Vision Eyeglasses Lens Types [9] About.com Vision How We See/Complications [10] About.com Vision Intralasik [11] About.com Vision Lasik Expectations [12] About.com Vision Lasik Surgery [13] About.com Vision Lasik Not Right for Everyone [14] About.com Vision Lazy Eye [15] About.com Vision Myopia Control [16] About.com Vision Correction Surgeries [17] American Academy of Ophthalmology Your Prescription [18] American Optometric Association Contacts [19] Cleveland Clinic Eyeglasses [20] Docshop.com Lasik Cost [21] Eyes-and-vision.com Contacts Versus Eyeglasses [22] FDA Contact Lens Risk [23] FDA Lasik Surgery [24] FDA Vision Correction [25] Kidshealth.org Kids and Glasses/Sports [26] Mayo Clinic Types of Contacts [27] National Eye Institute About the Eye [28] National Eye Institute Vision Impairments [29] National Federation of the Blind Legal Blindness [30]