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EyeFine.com Eye-Q

Lenses FAQ section.

This section provides you information about glasses lenses as optical systems, type of lenses, coating and materials.

Click on any of the questions below and get the answer.

Q: What single vision lenses are?

Single vision lenses are the most common type of eyeglass lenses. They are used for seeing objects in the distance (over four feet), and are good for all-around, every day use such as for driving, shopping, sporting activities, and walking.

Q: What bi focal lenses are?

Having one segment for near vision and one segment for far vision. Multifocals let you focus through different prescriptions at different distances through the same lens — hence the name. Bifocals (meaning a lens with two points of focus — usually one for distance and one for near) are the most commonly prescribed multifocal lenses. Bifocals are usually prescribed for those of us over the age of 40 who have lost their ability to focus on close work. They are a convenience, but are not necessary if your lifestyle needs can be met with single vision glasses.

Q: What is a progressive lenses?

Progressive lenses, sometimes referred to as no-line bifocals, not only provide visual correction for distances that traditional bifocals can't, but they also hide the fact that you even need reading glasses. No one else has to know whether you're sporting a pair of glasses just for fashion — or because your arms have "grown too short" to allow you to see up close.

Q: What plastic lenses are?

Plastic lenses are good for everyday use, around the office, or for shopping. For children or active adults engaged in sporting activities, we strongly recommend polycarbonate lenses. If the sphere on your prescription is +/-2.00 or lower, you will not benefit from the more expensive “thin” lens types (high index, or aspherics).

Q: What polycarbonate lenses are?

Polycarbonate lenses are not only thinner and lighter in weight than traditional plastic eyeglass lenses, they also offer ultraviolet (UV) protection and scratch resistance. In addition, they are very impact resistant. This extra toughness makes them the lenses of choice for children's glasses, sports eyewear and safety glasses.

Q: What HI Index lenses are?

Type of lens with a higher index of refraction, meaning that light travels faster through the lens to reach the eye than with traditional glass or plastic. It is denser, so the same amount of visual correction occurs with less material (whether glass or plastic) -- so the lens can be thinner. If you hate thick prescription eyeglasses, try lenses in a high-index material. They offer superior optics in a thinner, lighter lens.

Q: What antireflective coating is?

To improve both the vision through the lenses and the appearance of the glasses, an antireflective coating (also called AR coating) is applied. AR coatings are similar to the coatings found on microscopes and camera lenses. They consist of several layers of metal oxides applied to the front and back lens surfaces. Because of the layering effect, AR coatings sometimes have a hint of green or purple color, depending on the individual manufacturer's formula.

Q: What transition lenses are?

Transition lenses (also called variable-tint lenses or photochromic lenses) that darken in the sun are convenient for people who spend a lot of time outdoors. Here's a rundown of the many kinds of photochromic lenses now available for eyeglasses. Also: cosmetic lens tints and what they can do for your eyes and your looks.

Q: What polarized lenses are?

Tinted lenses with a polarization filter that blocks vertical light. good for boating, fishing, golfing, hunting, and driving (in dry conditions). eases eye stress and fatigue in the sun.

Q: What scratch resistanse coating is?

No eyeglass lens material not even glass is scratch-proof. However, a lens that is treated front and back with a clear, hard coating does become more resistant to scratching. Nowadays, most types of plastic lenses, including high-index, polycarbonate and traditional plastic materials, have built-in scratch-resistant coatings. Since it is sometimes optional, make sure your optician knows that you want scratch-resistant lenses in your prescription eyeglasses.

Q: What single ultraviolet coating is?

Another lens treatment that is beneficial but invisible to the naked eye is ultraviolet (UV) protection. Just as we use sunscreen to keep the sun's UV rays from harming our skin, UV treatment in eyeglass lenses blocks those same rays from damaging our eyes. Overexposure to ultraviolet light is thought to be a cause of cataracts, retinal damage and other eye problems. An ultraviolet treatment is simple and quick to apply to most plastic eyeglass lenses, and it does not change the appearance of the lenses at all. The exception is polycarbonate lenses, which don't need anti-UV treatment because it is an inherent property of the material.

Q: What VARILUX lenses are?

Varilux® Progressive Addition Lenses are the most technologically advanced lens available today for people with presbyopia. They allow you to see near, far, and everywhere in between without any distracting lines. Varilux progressive addition lenses are made from several different types of materials so you can choose the right lens for your lifestyles. The Varilux triple-patented Instant Focus System allows you to focus instantly at all distances.

Q: What do all those numbers in my prescription mean?

An eyeglass prescription is written in a standardized format with standardized notation so it can be interpreted worldwide. Let's look at one and break it down: -2.00 -1.00 x 180. The first number (-2.00) tells us the spherical refractive error (farsightedness or nearsightedness). In this case, because there is a minus sign in front of the 2.00, this patient is nearsighted. A plus sign would indicate farsightedness. The second number (-1.00) is the astigmatism. If there is no astigmatism, we generally write the letters DS or SPH after the first number to let the optician know that we didn't just forget to write in the astigmatism. There may be additional numbers in a glasses prescription. For instance, if the basic prescription is followed by a small number with a superscript (1^) it indicates prism correction. There may be more than one set of prism numbers for each eye. Lastly, there can also be numbers denoting the amount of near reading strength needed (bifocal or progressive). They usually go from +0.75 to +3.00, depending on age and visual need. The letters OD and OS in front of a prescription let us know which eye each string of numbers is for. OD stands for right eye and OS for left eye, while OU means both eyes.

Q: What pupillary distance is?

This is the distance between the center of each pupil. Opticians use a special ruler to measure your pupillary distance before ordering your eyeglasses. It is an essential measurement because the optical center of each eyeglass lens must be positioned directly over the center of each pupil. An incorrect measurement means you would have difficulty focusing when wearing the glasses.

Q: What photochromic coating is?

Lenses that keep up with changing light Lens colors that improve depth perception High Definition Optics® for unbeatable clarity

Q: What hydrophobic coating is?

Prevents moisture buildup Fights smudges and repels contaminants Makes it easy to keep lenses clean

Q: What Impact protection is?

Iridium® lens coatings optimize vision in bright light Photochromic technology enhances vision in changing light High contrast lenses improve depth perception in low light

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