Lenses are used for the correction of common visual impairments such as myopia, hyperopia, presbyopia, and astigmatism.
Lens Materials
Plastic (CR-39 ) lenses are currently the most commonly prescribed lens, due to their relative safety, low cost, ease of production, and high optical quality. The main drawbacks of many types of plastic lenses are the ease, by which a lens can be scratched (corrected with scratch coating), and the limitations and costs of producing higher index lenses.
Polycarbonate is lighter weight than normal plastic. It blocks UV rays, is shatter resistant and is used in sports glasses and glasses for children and teenagers. Because polycarbonate is soft and will scratch easily, scratch resistant coating is typically applied to the lens.
High-index refers to lenses with an index higher than 1.58. Aside from thinness of the lens, another advantage of high-index plastics is their strength and shatter resistance, although not as shatter resistant as polycarbonate. This makes them particularly suitable for rimless eyeglasses.
Trivex possesses the UV blocking properties and shatter resistance of polycarbonate while at the same time offering far superior optical quality and a slightly lower density. Another advantage that Trivex has over polycarbonate is that it can be easily tinted.
Lens Coating
Anti-reflective coating (AR coating) improves both your vision through your lenses and the appearance of your eyeglasses. This is due to the AR coating’s ability to eliminate reflections of light from the front and back surface of eyeglass lenses.
Anti-scratch coating is a film or coating that can be applied to optical lenses. It helps to prevent minor scratches that can easily happen to a regular lens. These minor scratches can damage the surface of the lens and impair vision. An anti-scratch coating acts as a protective layer thus making the lenses more durable.
Photochromics – Transitions these lenses darken when exposed to the sun and return to clear when indoors. Color-changing or photochromic lenses are comfortable to wear since they block harsh sunlight and convenient since you do not always need a separate pair of sunglasses when going outdoors.
Tints are colors added to lenses. Cosmetic lens tints fall into three categories:
Solids are tints of a single consistent color applied to the entire lens.
Gradients provide variable color throughout the lens, generally starting with a darker or greater depth of color near the top of lens, which gradually becomes lighter near the bottom.
Double Gradients contains two colors, generally starting with a darker or greater depth of color near the top of the lens, which melds into a second, lighter color near the bottom of the lens.
Contact Lenses
Contact lenses are thin lenses placed directly on the surface of the eye. Contact lenses are considered medical devices and can be worn to correct vision, or for therapeutic or cosmetic reasons.
Soft contacts are considered the most comfortable and are the most frequently prescribed type of contact lens. Soft contacts are available for all types of vision correction, including astigmatism and multi-focal needs.
Gas-permeable contacts or rigid contacts offer sharper vision, especially for people with high refractive errors or high degrees of astigmatism.
Hybrid contact lenses have a gas-permeable center surrounded by a soft outer ring.
Recommendations for Contact Lens Wearers
• Always wash your hands before handling contact lenses.
• Carefully and regularly clean contact lenses, as directed by your eye care professional.
• Store lenses in the proper lens storage case and replace the case at a minimum of every three months. Clean the case after each use, and keep it open and dry between cleanings.
• Use only products recommended by your eye care professional to clean and disinfect your lenses. Saline solution and rewetting drops are not designed to disinfect lenses.
• Only fresh solution should be used to clean and store contact lenses. Never re-use old solution. Contact lens solution must be changed according to the manufacturer’s recommendations, even if the lenses are not used daily.
• Always follow the recommended contact lens replacement schedule prescribed by your eye care professional.
• Remove contact lenses before swimming or entering a hot tub.
• See your optometrist for your regularly scheduled contact lens and eye examination.