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Knowing the terminology of Optometry can help you make better vision choices.
Here are a few of the most important terms related to contact lens wear and vision care. For further questions about these or other eye care terms, contact us.

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. Small amounts of astigmatism may be correctable with regular GP contacts.

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.

Clear front eye tissue that covers 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.

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. It is 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.

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 24 hours a day, for several days up to one week.

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 fit 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 obsolete.


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

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.

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.

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 fit with a contact lens for distance vision, and the other eye is fit for near vision. Although it is an effective technique, it does have disadvantages. For example, many people who use monovision report compromised depth perception.

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


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.

Ophthalmologists are medical doctors (M.D.s) 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.

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 O.D. or M.D. to fit contact lenses.

Doctors of optometry (O.D.s) 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.

Also known as ortho-K, this is 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.

With aging, the eye's lens becomes less able to focus incoming light. This results in blurred vision at reading distance, as well as eyestrain. Presbyopes may wear reading glasses, or multifocal contact lenses or glasses.

Abbreviation for photorefractive keratectomy, a surgical procedure in which an excimer laser removes corneal tissue to correct vision problems such as myopia.

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.

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.

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 is one type of refractive surgery.

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.

Abbreviation for radial keratotomy, a surgical procedure 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 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 lens
A contact lens design effective in correcting astigmatism.

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
When placing a GP contact lens on your eye, first put a drop or two of wetting solution on the bowl of the lens. This helps the lens adhere to your eye better. Wetting solution may also be used to relieve dryness after several hours of lens wear.
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