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Wednesday, December 19, 2012

CHOOSING LENSES

CHOOSING LENSES

TYPES OF LENSES
Review the various lens designs and choose what fits your lifestyle.
Single VisionSingle vision lenses function as all purpose glasses for persons who have normal accommodations. Persons who normally wear bifocals or trifocals can use single vision for distance or near (reading) lenses. Single vision lenses can also function as occupational glasses for certain types of work. Single vision lenses are available in all lens materials.
Bifocals (Flat Top)A flat top bifocal is a correction for distance and near vision in one pair of glasses. Flat Top 28 is the most popular bifocal form. It is also available with the bifocal portion made in a variety of widths (Flat top 35 and Executive Bifocals) to help with various close-up occupations. Flat tops are made in all lens material types.
Executive Style BifocalsSometimes used for those who need a wide field of vision for near work (accountants, for example), Executive Style Bifocals have a distinctive appearance and are thicker because of their design. They are generally only available in hard resin and polycarbonate.
TrifocalsTrifocals come in a variety of designs. Flat top trifocals are the most widely used form. The added segment provides clear vision at arm's length distance, the area that is usually blurred for bifocal wearers. Trifocals are available in all lens materials.
Progressives (no line bifocals)These lenses provide all the benefits of bifocals but add the feature of continuous clear vision at all distances, including mid-range distance (arm's length). Progressives have the cosmetic advantage to be single vision lenses so they never reveal the user wears bifocals. Progressives are available in all lens materials and also made in aspheric form. Because of their many benefits, they are becoming the lens of choice for bifocal and trifocal wearers.
Aspheric LensesThese new lenses provide special visual and cosmetic benefits for stronger corrections and increase edge to edge clarity. Flatter than conventional lenses, aspheric's eliminate the "bulgy" appearance of strong plus lenses (far-sighted corrections) and greatly enhance the appearance of finished eyewear. Persons with strong nearsighted corrections also benefit from thinner, lighter weight glasses when their lenses are aspheric. Because aspheric lenses are positioned closer to the face, there is less eye magnification with farsighted corrections and less "small eyes" look with nearsighted corrections. Aspheric lenses are often made of high index materials for the ultimate in thin lenses.
Sports GlassesAll sorts of special lens designs are available for the special needs of sports enthusiasts. Poly carbonate is usually the material of choice for active sports.
Computer GlassesThere are a variety of options for those who use computers. These include special filters and anti-reflection coatings.
Polarized Sun LensesThese are the exciting sunglasses that eliminate reflected glare. They are especially appropriate for drivers, fisherman, hunters and all types of outdoor activities.

LENS MATERIALS
Your first decision involves the material in which you want your new lenses made. When appearance and comfort are important, you may want lenses made in poly carbonate or high index. If active sports or work play a role in your lifestyle, you'll want to order poly carbonate Or, you may want lenses that automatically darken in sunlight. The following information will help you make your choice.
CR39 - PlasticConventional hard resin lenses are half the weight of glass lenses and can be tinted to almost any color and density. Hard resin lenses are more easily scratched than glass but can have an optional scratch protection applied. More impact resistant than glass, hard resin lenses do not require heat treating.
High Index Modern technology has created lenses that bend light differently so that stronger corrections are thinner than when made in conventional materials. Such lenses are called "high index" and stronger corrections are more attractive because they are slimmer. Glass lenses are also available with the slimming advantages of High index but are considerably heavier. High index plastic uses less material so they are often lighter in weight. High index lenses absorb all harmful UV light and can be tinted to any shade or color.
TransitionsThese are lenses that darken as you go from indoors to outdoors. They are available in both glass and lightweight hard resin. They darken to a moderate shade of grey or brown.
Polycarbonate
Poly carbonate lenses are the most impact resistant lenses available and are always the lens of choice for young people and active patients. Poly carbonate lenses are high index and are usually the lightest, most comfortable lenses. They absorb all harmful UV light and can be made with ultra thin edges because of their unique strength.
Varilux™Varilux lenses enable your eyes to make a smooth, gradual transition when you change your focus from near to intermediate to far vision. Unlike bifocal lenses, Varilux lenses eliminate the line that creates an abrupt, annoying vision change from near to far vision. The added comfort of Varilux is achieved with an increased field of vision. This larger vision field reduces unnecessary head movements both vertically and horizontally, which means you can assume a more natural, comfortable posture when viewing objects at close and intermediate ranges.
GlassFor years glass was the only lens material available and glass still offers superior optics. The most scratch-resistant material, the primary disadvantage of glass is its weight, generally twice that of hard resin. Glass lenses are heat or chemically treated to increase impact resistance.

LENS COATINGS & TREATMENT
TintAll lens materials except glass can be tinted in any color desired. Shades of any color ranges from 1 to 4 with 3 (ie. a grey #3) being the most common sunglass shade ordered. Solid and gradient tints are available.
UV ProtectionIt is generally accepted that the ultraviolet rays in sunlight pose potential harm to eyes. Specific treatment is available for plastic lenses that completely blocks hazardous UV light. Lenses like poly carbonate and high index include built-in UV protection at no extra cost.
Anti-Reflective CoatingSpecial anti-reflective coatings are now available for spectacle lenses, much like those used for fine camera lenses. These coatings are particularly effective for reducing eye fatigue for computer operators and anyone driving at night. And, of course, AR lenses enhance appearance by removing all distracting reflections.
Scratch ProtectionLight weight plastic lenses can be more easily scratched than glass. Eye Deal Eyewear offers a one time replacement warranty against scratches during the first year.

HOW SHOULD I LOOK AFTER MY EYEGLASSES?
• DO NOT place them face down.
• DO NOT put them on and take them off with one hand as this can stretch the joints.
• DO NOT clean plastic lenses with tissues.
• DO keep them in a case when not worn.
• DO clean them with a soft cloth and suitable cleaning fluid or a drop of warm water and detergent.
• DO come back and have your frame adjusted if required - There is no charge for this.
• DO remember that if you are dependant on your eyeglasses for driving or for your work you should
consider a spare pair in case of loss or breakage. Many people don't think about this until it is too late.


STANDARD
LENS POWERS RANGE Sphere Powers: +/-6.00 diopters in .25 increments Cylinder Powers: -3.00 diopter in .25 increments Bifocal Style: Flat top-28mm segments with adds up to +3.00

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