Lens Materials
Glass Lenses
Glass is the original material used for corrective lenses. While glass lenses offer exceptional optics, it is the heaviest and thickest lens material available. Due to the tendency for glass lenses to break easily, risking serious injury to the eye and orbit or even loss of an eye; glasses lenses are no longer commonly utilized.
Plastic Lenses
Conventional plastic lenses, also known as hard resin lenses, are about half the weight of glass lenses. Plastic lenses are suitable for mild to moderate powered prescriptions and are easily tinted for shade or fashion. Because they are less scratch resistant than glass, they should be paired with a scratch-resistant coating.
Polycarbonate and Trivex Lenses
Polycarbonate is the most impact resistant material available for ophthalmic lenses. It is used for children, teens and those needing extra protection for their eyes. Thinner and lighter than plastic, polycarbonate and trivex are frequently used for those with a moderate power prescription. Polycarbonate also provides UV protection.
High Index Lenses
High index lenses bend light differently than conventional materials providing better visual acuity for high prescription patients. Lighter and thinner than polycarbonate or plastic lenses of the same prescription they are also much more comfortable to wear, frequently making them the lens of choice. Designed to absorb all harmful UV rays, they can be tinted to any shade or color.
Lens Enhancements
Photochromic Lenses
Photochromatic lenses, also known as transitional lenses, change from clear to tinted with exposure to UV light and are available in most lens materials. Photochromatic lenses reduce eye strain from sun exposure and may provide comfort in bright conditions but may not darken as fully as sunglasses inside a car if the windshield is designed to block UV rays. Some people find they still require sunglasses for activates like fishing and outdoor sports.
Polarized Lenses
Polarized lenses use a dark filter to reduce sun glare from surfaces like water, snow and sand. They are great for outdoor activities and driving and are available in most lens materials. Polarized lenses may make it difficult to see the liquid crystal display on your car’s dashboard and some electronic devices.
Anti-Reflective Coating
Anti-reflective (AR) treatments, like those used for fine camera lenses, are particularly effective for reducing eye fatigue from computer use, artificial lighting and driving at night. AR lenses enhance the appearance of objects by removing distractive reflections. They are also smudge and water resistant.
Scratch Resistant Coating
Scratch resistant coating should be applied to all forms of plastic lenses. The addition of this protective coating helps reduce the amount of scratches that occur from normal use.
UV Protection
Ultraviolet treatment is available for hard resin lenses completely blocking hazardous UV light. Ultraviolet rays can be harmful to our eyes, contributing to conditions like cataracts and macular degeneration. Polycarbonate and high index lenses include built-in UV protection.
Tint
A variety of colors can be added to lenses for cosmetic appeal and many are available in both solid and gradient versions. Dark tints such as green, gray or brown are frequently used for sunglasses and yellow can provide increased contrast for those needing enhanced night driving as well as for hunters or those who utilize weapons for work or pleasure. Solid and gradient tints will shade your eyes and provide comfort from the sun but tinted lenses will not fully reduce glare.
Mirror Coatings
Mirror coatings come in a variety of colors like silver, gold and blue and are highly reflective. Often paired with polarized lenses, mirror coatings are mostly used for outdoor activities and some professional use. The highly reflective properties of mirror coating reduce heat and glare and can enhance the comfort of the wearer.
Lens Designs
Single Vision
Single vision lenses are most commonly used for traditional farsightedness, nearsightedness and astigmatism corrections; but an individual who generally wears bifocals or trifocals may also use single vision for distance, reading or in specialty lens situations. Single vision lenses are available in all lens materials.
Flat Top Bifocal
Flat top bifocals are a single vision lens with an additional lined bifocal in the lower part of the lens to accommodate various reading requirements. Lined bifocals typically require the wearer to look through the top portion of the lens for distance and through the lower portion for near vision. Bifocals are usually made in distance/near corrections but specialty computer/near corrections are also available. Bifocals are available in all lens materials.
Trifocals
These are essentially a flat top bifocal with a third section designed for intermediate correction. The added segment, which sits above the bifocal portion, provides clear vision at arm’s length. This additional area works well for computer screens and driving, correcting the area that is frequently blurred for lined bifocal wearers. Trifocals come in a variety of widths and are available in all lens materials.
Progressive Lenses
Progressive lenses provide clear, continuous vision from distance to near correction with no visible lines similar to the eye’s natural function. The cosmetic advantage of being an invisible bifocal appeals to most wearers. Progressive lenses are available in all lens materials and are more youthful and cosmetically appealing. Because of their many benefits, these are frequently the preferred lens choice for those requiring bifocal or trifocal correction.
High-Definition (HD) Lenses
HD lenses are most common in progressive lenses, but also available for single vision wearers. HD lenses are made using digital computer technology and tools that allow the lens to be customized to a person’s individual prescription. They provide superior clarity and sharper, brighter vision for nearsighted, farsighted, astigmatic and progressive lens wearers. They are easy to adapt to and are available in all plastic lens materials.
Occupational (Safety) Lenses
Many occupations impose demanding visual requirements on those who wear eye glasses. Special occupational lens and frame designs are available to solve these special needs providing safety on the job.