A Glossary of Vision Terms

Below are some common terms used on the Vision Direct site and by eye care professionals.

 

Astigmatism:

Astigmatism is a condition in which the cornea's curvature is asymmetrical, resulting in blurred vision. Astigmatism is one of the most common vision problems affecting people with farsightedness or with nearsightedness. Usually it is caused by an irregularly shaped cornea (called corneal astigmatism). But sometimes lenticular astigmatism results from an irregularly shaped lens, which is located behind the cornea.

 

Bifocal Lens:

A bifocal lens is a lens with one segment for near vision and one segment for far vision.

 

Color Tint Lenses:

This type of lens will dramatically change the color of your eyes regardless of whether you light of dark eyes.

 

Concentric Bifocal Pattern Lens:

This is the most commonly used lens for bifocal and multifocal lenses. With a concentric bifocal pattern contact lens, the near correction is located in a small circle at the center of the lens and is surrounded by a larger circle that contains the distance correction. This can be flip-flopped where the distance correction is in the center and the near correction is in the outer ring.

 

Enhancement Tint:

These contacts are designed to enrich, but not dramatically change the natural hue of your eyes. This type of lens is ideal if you want to make your original color deeper or more intense. These tinted lenses are ideal for people who have lighter hues in general and do not work well for those with dark eyes.

 

Enzymatic Cleaner:

A cleaner that removes protein deposits as well as other debris from contact lenses.

 

Farsightedness:

Also called Hyperopia. This is a common condition where the length of the eye is too short, causing light rays to focus behind the retina rather than on it. Farsightedness results in blurred near vision.

 

Handling Tint:

Lenses that say “handling tint” are slightly tinted to make them more visible for both care and insertion of the lens. The tint on these lenses has no effect on eye color.

 

High-Index Lens:

A High-Index lens is a type of lens with a higher index of refraction. This means that unlike traditional glass or plastic, light can travel faster through the lens to reach the eye.

 

Hybrid Multifocal Lens:

A multifocal contact lens that is soft around the peripheral with a gas permeable center.

 

Hyperopia:

See farsightedness.

 

Monovision:

A vision correction method for people with presbyopia in which one eye is corrected for near vision and one eye for far.

 

Multifocal Lens:

A contact lens design that includes more than one focal area, such as bifocals and trifocals.

 

Nearsightedness:

Also called myopia. With myopia, visual images come to a focus in front of the retina, which results in blurred vision of distant objects.

 

Myopia:

See nearsightedness.

Presbyopia:

The natural loss of close-up vision as one gets older. Presbyopia is caused by inflexibility of the eye's lens, a condition that prohibits the eye from focusing properly on objects up-close.

Theatrical Lenses:

Contact lenses that will give a special effect, you can purchase theatrical lenses.

Replacement Schedule:

How often you discard and replace your contact lenses. It's important to differentiate between a replacement schedule and a wear schedule.

RGP (Rigid Gas Permeable):

Type of contact lens made of breathable plastic that is custom-fit to the shape of the cornea. RGPs are the updated version of hard lenses.

Soft Lenses:

Contact lenses made of gel-like plastic containing varying amounts of water.

Solution:

Product used to clean, disinfect, and store contact lenses.

Spherical:

A contact lens design that is like a sphere.

Toric:

A lens design with two different optical powers at right angles to each other for the correction of astigmatism.

Trifocal:

A lens design that has three focal areas: a lens for close-up, a lens for mid-distance, and a lens for faraway.

Wear Schedule:

Wear schedule is the length of time you wear your contact lenses per day – either daily wear (removed before sleeping) or extended wear (you may sleep with them in).