Types of Lens Designs
Single vision lenses are designed to correct for one focal point. They are prescribed for distance viewing, reading, or arm's length ranges. They are effective when used for the range they were designed. For example, reading glasses help bring near objects into focus, but will blur your vision during driving and lenses prescribed for using the computer will not allow you to see clear for very close work or watching TV. Most materials and coatings are available in this lens.
Bifocal lenses are designed to correct for two separate focal points. They are typically prescribed for both distance and reading ranges. A person with a lined bifocal lens will be able to see distant objects clearest through the top portion of the lens and objects up close will be clear through the lower portion. There are numerous styles of lined bifocals to choose from depending on your needs. The disadvantage of this lens is that any object located at arm's length will not be in focus. Objects in this area will have to be brought closer until it is in the reading portion of your lens. Trifocal or no-line bifocals (progressives) may be the best option for patients that use the arm's length range extensively. Bifocal lens may also be prescribed specifically for computer only use.
Progressive (no-line bifocals)
Progressive lenses are the most versatile designs available today. They are designed to simulate your natural vision. There is a transition of power in progressive lenses. When a person looks at an object in the distance, it will be in focus. As a person lowers their eyes, they will notice the gradual change in power in the progressive. The power continues to change until it becomes your prescribed near correction. This gradual change offers patients the ability to see objects at any range clearly with the adjustment of their head. To receive the best possible vision with this lens, people must train themselves to point their nose at the object to be seen. Although there is a period of adjustment necessary to fully adapt to progressive lens, they offer the most natural vision of all the available lenses.
Polarized lenses are the best possible sunglass lenses for your eyes. They eliminate reflected glare. The lenses are designed for people that are very sensitive to sunlight. People that spend time near water or a lot of time driving will benefit from polarized. Harmful ultraviolet rays are filtered by this lens. Typically eye fatigue caused by excessive glare is reduced.
Anti-Reflective lenses are designed for people with night driving difficulties due to glare from lights. Anti-Reflective lenses reduce the "starburst" effect that many people encounter while driving. Computer users also benefit by having this lens because it relieves eyestrain from glare prone computer monitors. The lenses are typically reflection-free allowing your eyes to show through in photographs.
Hi-Index lenses are the thinnest lenses available today. With stronger prescriptions, less material is used in hi-index lenses than regular plastic or glass, making the lenses both lighter and thinner. With the reduced amount of material used with hi-index lenses, patients receive the added benefit of lighter weight. Ultra-violet protection is also provided by this clear lens material. Patients with very strong prescriptions notice the biggest benefits of hi-index lenses, especially when combined with the anti-reflective treatment.
Polycarbonate is the safest material available in eyewear today. With its impact resistance, it is the most logical choice for children. Polycarbonate lenses protect a child's eyes in situations that their eyewear can be struck by objects and during falls. Everyone should have the added safety of protection from eye injuries. Although sports are a major cause of eye injuries, people of all ages and lifestyles are in danger of flying objects. Lawncare, falls and workshop hobbies are other contributors to injured eyes. Ultra-violet protection is also provided by this clear lens material.