THIS MONTH SPECIALS:
- *Free single vision (CR39) lenses (sph ± 3.0, cyl. -2) with $129 and up frame purchase
- *Photochromic grey (CR39) lenses (sph ± 2.0, cyl. -2) only $139
- *Progressive (CR39) lenses for only $149
- *Bifocals FT28 (CR39) lenses for only $75
*Restrictions apply. Please call store for details.
PROVIDED BELOW IS INFORMATION REGARDING DIFFERENT TYPES OF LENSES AND COATINGS.
Eyeglass lenses are classified into four basic categories:
SINGLE VISION lenses have the same focal power and can be used to correct nearsightedness, farsightedness, astigmatism, or a combination of these ailments. Most people who wear glasses before the age of 40 have single vision lenses.
BIFOCAL lenses consist of two parts. The upper part is normally used for distance vision and the lower part is used for near-vision. The near-vision lens is mostly commonly used for reading. After reaching the age of 45, many people develop a condition called presbyopia. This condition is caused by the inability of the eye’s natural lens to expand or contract in order to focus on close objects. People with presbyopia need special lenses for reading and may need a different type of lens for distance vision. Benjamin Franklin invented bifocals so he would not need to switch glasses.
TRIFOCAL lenses have three different focus areas. The top is for distance vision, the center is for intermediate vision, and the bottom is for near vision. Bifocal lenses are designed so that the line of division is at the level of the lower eyelid. However, trifocals are fitted higher to provide comfort.
In addition to bifocal and trifocal lenses, one other popular MULTIFOCAL lenes is a PROGRESSIVE addition (no-line bifocal) lens that increases in power from top to bottom. Progressive lenses have no clear dividing lines as the focus changes from bottom to top. They have become very popular in recent years because they look like single vision lenses.
Aspheric lenses aid in cutting down the thickness and weight of lenses, especially when combined with high-index materials. Aspherics have curves that are nonspherical and change gradually from the center to the outside of the lens. Aspheric lenses are now available in single-vision, bifocal, and progressive-addition designs.
Photochromic lenses change in color and light transmission when exposed to different light intensities. The rate of darkening depends on the ambient temperature. These lenses do not become to dark when driving because the car’s windshield absorbs some of the ultraviolet light that causes the lenses to darken. Photochromic lenses are now available in plastic, polycarbonate as well as glass, and come in grey and brown colors
Polarizing lenses are very useful in protecting the eye from reflections when skiing or participating in water sports. They are available in plastic, glass, and high-index materials to provide comfort and accuracy for sports enthusiasts.
Mirror-coated lenses are coated with a layer of reflective material that greatly reduces the amount of heat stimulating the eyes. However, these lenses reduce visual accuracy. This kind of coating is purely cosmetic and frequently seen on glasses worn by state troopers. Mirror coatings come in a number of colors and are highly reflective. They usually are applied on sunglass-dark lenses.
Anti-reflective coatings (A-R coatings) are metallic oxide coatings that are vacuum-applied to the lens surface to reduce reflections from the front lens surface and eliminate reflections from the back. This reduced amount of reflection enhances the appearance of the glasses and also allows more light to pass through the lenses, which can improve vision in low-light situations. Anti-reflective coatings also provide some protection from scratching
Ultraviolet protective lenses protect the eyes from ultraviolet sun rays that have been shown to cause cataracts and certain diseases of the eye. If you spend a lot of time outdoors, it’s important that lenses are anti-UV coated. The best eye protection from UV radiation is a good pair of sunglasses that is rated to block 99 percent to 100 percent of the full UV spectrum. UV coating can be applied to all glass and plastic lenses, except polycarbonate, which doesn’t need coating because it absorbs virtually all the UV rays.
Scratch-resistant coatings (also known as “hard coat”) are applied to the front and back surfaces of lenses to protect against accidental scratching and to improve durability. No coating can make lenses completely scratch proof.