Wiley X PT-1 Sunglasses

Single Vision - A single lens is used for a certain distance. (ie reading, far away etc...). Many people can use the same lens for both distance and near, especially if they are under the age of 40.

Bifocal - A Bifocal is lens that has two sections divided by a line. Usually the top portion is used for distance and the bottom portion is used for reading.

Trifocal - A lens that has three sections divided by lines visible on the lens. Usually the top portion is used for distance, the middle portion is used for an intermediate distance, and the bottom portion is used for reading.

Progressive Level I - A basic progressive lens that has various areas of focus throughout without any lines on the lens. Usually the top portion is for distance, the middle portion is for an intermediate range and the bottom portion is for reading.

Progressive Level II - A progressive lens that provides the same type of vision as a level I, but also provides a higher degree of optical quality as well as larger viewing area than level I.

Progressive Level III - A progressive lens that provides the same type of vision as a level I progressive, but also provides a greater viewing area than the other progressives and also offers a higher degree of optical quality as well as larger viewing area than Level I or Level II.

CR39 - Plastic - A basic plastic lens that may be used for prescription lenses. This lens is not recommended for most prescriptions, as it does not provide the impact resistance that the polycarbonate lenses provide. It is also a thicker material than all the other lens materials.

Polycarbonate - An impact resistant lens that is recommended for all glasses for the protection of the eyes behind them. It is also a thinner material than standard plastic lenses.

High Index - A material used for making lenses thinner. An index value of 1.67 is thinner than plastic, while an index value of 1.74 is thinner than both.

High Index Level I - An index value of 1.67. This is thinner than the plastic lens, but not as thin as the level II high index lens.

High Index Level II - An index value of 1.74. This is thinner than all the above lens options. Usually used for very high prescriptions to minimize the thickness of the lens.

Clear - Does not reduce light transmission or contrast. Usually made out of polycarbonate lens material for the purpose of enhancing vision with a prescription and/or protecting eyes from impact or debris.

Light - A light shade of tint recommended for low light conditions. (Not recommended for direct sunlight)

Medium - A medium shade of tint recommended for use where sunlight is dawn or dusk conditions. (Not Recommended for direct sunlight)

Dark - A dark shade of tint recommended for use in direct sunlight. Dark lenses are not recommended for use in dawn or dusk light conditions.

Gradient - Gradient lenses are tinted dark on the top of the lens and gradually fade to a light tint shade at the bottom of the lens.

Amber Tint - Filters out blue light for enhanced contrast and depth perception. Works well in all light conditions.

Blue Tint - Blue is high contrast color, usually selected for the look of the appearance of the lens.

Brown Tint - Brown lenses enhance contrast and are a great choice for an all around sunglass lens color.

Grey Tint - Grey lenses flatten light and are the most popular lens color due to its wide variety of uses.

Transitions - Transitions lenses quickly adapt between indoor and outdoor conditions, offering a distinct advantage over ordinary clear lenses. Transitions Lenses adjust from clear to dark when exposed to UV light, therefor will not properly function when in a car due to the UV protection provided by your cars windsheild.

Drive-wear - Drivewear lenses are similar to Transitions Lenses, yet are capable of sensing and reacting to varying light conditions both outside and behind the windshield of the car.

UV Protection - Protects the eyes from harmful ultra violet rays that cause cataracts and other diseases in the eye.

Anti-Reflective Coating - Minimizes glare ie: from oncoming headlights, computers, overhead projectors in school

Polarized Lenses - Minimizes glare and aids in overall viewing. Especially used for skiing, fishing and boating.

Sphere - The overall power of a lens used to correct vision.

Cylinder - The power of the lens designated to correct for astigmatism (irregular shape) of the eye. This number adds (or subtracts) power from the lens at a certain area to compensate for the different prescription the eye has in a certain location.

Axis - A number between 1 and 180 in degrees to designate the axis of curvature for which the extra correction for astigmatism (the cylinder) is added or subtracted.