Glossary

Astigmatism

A condition where the cornea is irregularly shaped, causing distorted vision especially at near distances. Either glasses or toric contact lenses can correct astigmatism for most people. Up to moderate amounts of astigmatism are correctable with regular GP contacts.

Bifocal

A type of spectacle or contact lens design that includes two focal areas: one for near, one for distance.

Cleaning solution

When cleaning contact lenses, the first step is often to apply a few drops of cleaning solution to the surface and rub gently for about 20 seconds. The solution and the rubbing work together to loosen any debris, which is then rinsed off with saline solution. The next step? Disinfection and storage.

Contact lens technician

In many states, contact lens dispensing may be handled by specially trained technicians, who fit the lenses after an optometrist or ophthalmologist determines the prescription.

Cornea

Clear front eye tissue that covers the iris and pupil and admits light. Contact lenses either fully or partially cover the cornea.

Daily wear lens

Worn during waking hours and removed at the end of each day for cleaning and disinfecting.

Disinfectant

Agent that inhibits the growth of or destroys harmful microorganisms such as bacteria.

Disinfecting/soaking solution

After cleaning contact lenses and rinsing them with saline, fill the chambers of your storage case with enough disinfecting solution to cover the lenses. Always use fresh disinfecting solution. Allow your lenses to soak and disinfect overnight.

Disposable contact lens

Worn for brief periods, from one day to two weeks, then discarded and replaced with a new lens.

Dry eye syndrome

Dry eye usually occurs when eyes don't produce enough tears or when tears evaporate too quickly because of environmental conditions. Contact lens wearers, computer operators, post-menopausal women, and people with allergies are most susceptible to chronic dry eye.

Emmetropia

The scientific term for normal vision. When the cornea and lens of the eye focus an image directly on the retina, clear vision is the result.

Enzyme cleaner

An extra-strength cleaner, typically used weekly, to remove stubborn deposits from contact lenses. Comes in versions for both soft and GP lenses.

Extended wear lens

Worn without removal for sleeping. Most extended wear lenses are worn continuously for a week; several brands are approved for 30-day wear.

Farsightedness

A condition where the eyeball is too short and flat, so that light rays haven't yet focused when they reach the retina. The result is difficulty in seeing near objects clearly.

GP contact lens

Also known as a gas permeable or RGP (rigid gas permeable), this contact lens is made of breathable plastic that has been custom fitted to the shape of the cornea. GP contact lenses are long-lasting, comfortable, easy to clean, and healthy for the eyes.

Hard contact lens

Made of an inflexible plastic material called PMMA (polymethylmethacrylate), this was the first contact lens in wide use. Hard lenses had excellent optics, but because they kept oxygen from reaching the cornea, they've become virtually obsolete.

Hyperopia

Farsightedness.

Iris

The colored portion of the eye, the iris regulates the opening of the pupil.

Keratoconus

A condition where the cornea becomes cone-shaped, causing major vision distortion. People with keratoconus are particularly challenging to contact lens fitters, who usually must prescribe custom-made lenses for them.

LASIK

Abbreviation for laser-assisted in-situ keratomileusis, a surgical procedure in which a tiny flap is cut in the top of the cornea, underlying corneal tissue is removed with an excimer laser, and the flap is put back in place. The surgery corrects vision problems such as nearsightedness, farsightedness and astigmatism.

Monovision

This is a contact lens fitting technique that is an alternative to bifocal glasses, bifocal contacts, or reading glasses. It may be used with either soft or GP contacts. One eye is fitted with a contact lens for distance vision, and the other eye is fitted for near vision. Although it is an effective technique, it does have disadvantages. For example, many people who use monovision report compromised depth perception.

Multifocal

A type of spectacle or contact lens design that includes more than one focal area. Bifocals and trifocals are both multifocal lens designs.

Myopia

Nearsightedness.

Nearsightedness

A condition where the eyeball is too long and steep, so that light rays focus before they reach the retina. The result is difficulty in seeing distant objects clearly.

Ophthalmologist

Ophthalmologists are medical doctors (MDs) who are eye specialists. They perform eye examinations, treat disease, and perform surgery; some also specialize in contact lenses. In some states ophthalmologists may have opticians and contact lens technicians working with them, who are specially trained to fit contact lenses.

Optician

Opticians and contact lens technicians are not doctors, but in some states they can become certified, after special training, to fit contact lenses. Some specialize in contact lenses and work in optometric or medical offices, working as a team with an OD or MD to fit contact lenses.

Optometrist

Doctors of optometry (ODs) complete four years of post-graduate optometry school. Optometrists examine eyes for both vision and health problems, prescribe glasses, and fit contact lenses. They can prescribe many ophthalmic medications and often participate in pre- and post-operative care.

Orthokeratology (ortho-k)

A non-surgical procedure for changing the shape of the eye's cornea. The procedure involves wearing a series of GP contact lenses that progressively "mold" the surface of the cornea into a shape that provides for better vision. The procedure does not have a permanent effect. Therefore, just as orthodontic retainers keep your teeth from moving back to their original positions, "retainer" contact lenses must be worn periodically to keep the cornea from regressing back to its less desirable shape.

Presbyopia

The age-related inability to focus clearly at all distances. Presbyopes may wear reading glasses, multifocal contact lenses, or glasses.

PRK (photorefractive keratectomy)

A surgical procedure, similar to LASIK, in which an excimer laser removes corneal tissue to correct refractive error. In PRK, surface tissue is removed; in LASIK, a flap is cut and tissue is removed below the eye's surface.

Progressive addition lenses

Like bifocals and trifocals, progressive lenses provide clear vision at all distances: near, intermediate, and far. The difference is that the viewing zones gradually blend into each other, for lenses that are more attractive to wear.

Pupil

The small dark portion in the center of the eye, the pupil opens and closes to regulate the amount of light, and thus the amount of visual information, the retina receives.

Refraction

A measurement of the eyes to determine the level of visual acuity. Most refractions are performed by optometrists, though many ophthalmologists do them as well. Refractions often result in a prescription for glasses or contact lenses.

Refractive surgery

Any type of surgery, whether performed with a blade, laser, or waterjet, that corrects visual acuity. LASIK and PRK are types of refractive surgery.

Retina

Thin tissue in the back of the eye that receives an image formed by the lens and converts it to electrical impulses carried by the optic nerve to the brain.

Rewetting solution

Drops that contact lens wearers can use all day if needed to keep the eye moist.

RGP contact lens

Abbreviation for rigid gas permeable lens. Same as GP (gas permeable) contact lens.

RK (radial keratotomy)

An early and now obsolete type of refractive surgery in which cuts are made in the cornea in a radial pattern, to flatten the cornea and correct myopia.

Saline solution

Sterile salt solution used to clean and store soft contact lenses. Saline is also used to rinse both soft lenses and GP contacts.

Soft contact lens

Made of gel-like plastic, soft contact lenses contain varying amounts of water. They provide good initial comfort for first-time wearers but must be replaced often.

Toric contact lens

A contact lens design for correcting astigmatism.

Trifocal

A type of spectacle or contact lens design that includes three focal areas: usually a reading lens, a lens for faraway viewing, and a lens for mid-distance viewing.

Wetting solution

Drops used to ease the process of applying a GP lens to the eye. Wetting solution may also be used to relieve dryness after several hours of lens wear.

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Frequently asked questions

Who can wear contact lenses?

Most people can. Whether you're nearsighted or farsighted, older or younger, you can probably wear some type of contact lens. Contact lenses can correct your astigmatism, and multifocal contacts can help those with presbyopia to have crisp near, intermediate, and distance vision.

Are contacts good for my eyes? Can they damage my cornea?

Contact lenses have proven to be a healthy vision option for millions of people. But only your eye care professional can determine if they are healthy for you.
If you follow all prescribed steps for inserting, removing, and caring for them, contact lenses will continue to be safe and effective. You also need to see your eye care professional regularly to ensure long-term corneal health.

At what age can contact lens wear begin?

As soon as the need for vision correction is identified, contact lenses are a viable option. In fact, they have frequently been used in premature infants, who sometimes have vision problems. With proper care and lens maintenance, infants, young children, teens, and adults of all ages can wear contacts successfully.

Should I wear contact lenses while playing sports?

Sports vision doctors agree that contact lenses are the best vision correction option for athletes. They can enhance visual skills like depth perception, peripheral awareness, and eye-hand/eye-foot coordination.
Unlike glasses, contacts offer athletes a competitive advantage because they stay in place under dynamic conditions, provide a wider vision field, and eliminate the risk of glasses-related injuries. Contact lenses also make it easy to wear protective goggles.

Can some contacts actually slow or control nearsightedness?

Many contact lens specialists agree that GP contact lenses, which are made of firm plastic, may slow the progression of nearsightedness (myopia). Myopia control is one reason why GP contacts are an excellent choice for many school-aged children and teens. Various eye care practitioners are continuing research in this area.

If I have astigmatism, can I wear contact lenses?

Yes. Astigmatism is distorted vision caused by an irregularly shaped cornea. Contact lenses for astigmatism are called toric lenses, and they come in both soft and GP contact lens materials.
GP contacts tend to work better for astigmatism, because they are custom-fit to your eyes' particular shape; also, their firm material keeps its original shape more when you blink. In addition, moderate amounts of astigmatism may be corrected with a regular, non-toric GP contact lens.

Aren't soft contact lenses the newest and best technology?

No. When they were first available in 1971, soft contact lenses were a giant leap in technology and comfort over old-style hard contact lenses.
But GP contact lenses, first marketed in 1978, are a next-generation advancement. New, recently developed materials and designs make them a state-of-the-art option for contact lens wearers, offering sharper vision, better corneal health, longer lens life, and greater ease of care than most soft contacts.

Are contacts hard to take care of?

It differs from lens to lens:
GP contacts, which last for years, need daily cleaning and disinfecting, but their slick surface resists deposit buildup.
Daily disposable soft lenses are worn once, then discarded, with no maintenance required.
Other disposable soft lenses are usually cleaned at the end of the day, then soaked in disinfecting solution until they're worn again, and may be replaced weekly, bi-weekly, or monthly.
Soft lenses that are replaced quarterly or annually might require weekly enzyming in additional to daily care. 

How can I get contact lenses that change my eye color?

Soft contact lenses are available that will change the color of your eyes, even if you don't require vision correction. Costume lenses for Halloween or theatrical purposes are also available.
GP contact lenses sometimes have a color "handling tint" — a light tint that makes them easier to see — but GPs are not available in colors that will change the appearance of your eyes. A GP lens is smaller than the size of the iris, so GP color lenses would not look natural.
All color contacts are prescribed medical devices that must be fitted and followed up by your eye care professional. And remember, even though such lenses might provoke curiosity by your friends and family members, never share them with anyone. Sharing lenses can lead to dangerous health problems.

How much do contact lenses cost?

The cost of contact lenses can vary greatly. If you have a difficult prescription or need correction for problems like astigmatism, your lenses will be more expensive. If you have no special requirements, your options will range from daily disposables (the highest cost) to GP contacts, which are thought by many to provide the greatest value. GP contacts, though initially more expensive, can last for years and are inexpensive to care for.
Consumer Reports called GP contact lenses a better buy "because they're more durable and cheaper to maintain." Fortunately, GP contacts can also accommodate any prescription, no matter how difficult, because they are custom-made for each individual wearer.

Can I sleep in my contact lenses?

Ask your doctor. It depends on the type of lens you're wearing, the composition of your tear film, your general eye health, and other factors.
GP contact lenses and certain soft lenses can be slept in, but never wear them while sleeping unless your eye care practitioner says you can.

’ I can’t open my eyes wide enough. ’

Yes, you can. Just grab the upper eye-lid with your index finger and thumb and gently separate eye-lids.

’ My eyes are too small. ’

They are not. Hold your upper eye-lid and put edge of the contact lens slightly under bottom eye-lid, so the lens is leaning out. If you look downwards, contact lens will usually posture itself on the eye correctly.

’ What if I put contact lens on a wrong place? ’

You can’t. Lens won’t be at standstill unless aligned properly, and it has natural tendency to move towards the center of the eye. Your ophthalmologist can show you how to adjust it to a right position if it slides from the cornea.

’What if lens slides behind the eye-ball? ’

Don’t worry, that is completely impossible.

’My contact lens won’t stay on position.’

That usually happens when contact lens is put on more humid surface, and your finger is more humid than your eye. Dry your finger and keep lens in air for a few seconds so it can dry a bit too before you place it.

’ I’m afraid I’m going to put it upside-down. ’

Good thing about GP contact lenses it that they can’t be turned upside-down. But if your lenses are soft than look carefully. If the edge is wide and flat than it is upside-down. Some soft lenses have markers that help u distinguish top and bottom side.

’ How to remove lens? Isn’t it glued to my eye? ’

No. If you are wearing GP contact lens, just pull your eye-lid sideways and blink. It will come out. For soft contact lenses use moisture drops or solutions. Look up, touch the lens and let it slide downwards over the cornea. Then pluck it out.

’ Am I going to have eye problems if I touch lenses? ’

No. Just make sure that your hands are always clean.

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History of contact lenses:

1508   Leonardo da Vinci illustrates the concept of contact lenses
1823   British astronomer Sir John Herschel conceptualizes practical lens design
1887   First contact lens manufactured from glass, and fitted to cover the entire eye
1939   Contact lenses first made from plastic
1948   Plastic contact lenses designed to cover only the eye's cornea
1971   Introduction of soft contact lenses
1978   Introduction of GP contact lenses
1981   FDA approval of new soft contact lenses for extended (overnight) wear
1986   Overnight wear of GP contact lenses becomes available
1987   Introduction of disposable soft contact lenses
1987   GP contacts available in next-generation fluorosilicone acrylate materials
1996   Introduction of one-day disposable soft lenses
2002   Silicone-hydrogel contact lenses first marketed
2002   Overnight orthokeratology approved by FDA
2010   Custom-manufactured silicone-hydrogel lenses become available

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Instructions for use:

Leda Perm - RGP contact lenses (PDF document)

Leda Soft - soft contact lenses (PDF document)


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