Lens Types for single vision.
Standard Plastic (CR-39) offers good optical clarity at a great value and price. This lens does not provide good UV protection and scratch resistance. It is not available in a advanced flat design and for safety reasons is not recommended for children.
Polycarbonate lenses are thin, light weight, shatter resistant, scratch resistant and provide UV protection. This is the lens of choice for kids eyewear, sports eyewear and safety eyewear.
Polarized lenses provide complete protection from the sun. It helps to enhance our visual acuity and color contrast by eliminating glare, improving our depth perception and reducing eye strain. It is great for outdoor recreation.
Lens types for bifocals:
Lined bifocals work like two single vision lenses. The top half corrects for distance prescription ( ie nearsighted, farsighted, and/or astigmatism and, the bottom half corrects for near. When looking down with lined bifocals, you will experience abrupt focus changes from far to near. There is no intermediate focus.
Trifocals work like three single vision lenses. The top third for distance, the middle for intermediate distances (ie computer screen), and the bottom for near.
No line progressives (good design). Progressive lenses work like multiple lenses in one. The top half corrects for the distance prescription, below straight ahead corrects for intermediate distances, and the bottom corrects for near vision.
You will experience smooth continuous vision. You will also experience good viewing side to side. You may notice areas of "soft" focus toward the edge of your lens when viewing at near. This design may take some time learning to use.
No line progressive (better design). You will enjoy all the benefits of a good design lens, but you will experience wider areas of sharp focus and less side to side head turning at near. You will see a more fully usable lens surface. These lens designs are easiest to learn to use.
Lens treatments include:
Non-Glare coatings enhance vision by removing glare and halo. You will see more clearer and sharper because it allows more light to pass through the lens.
Out tints reduce improves comfort and reduces eye strain by decreasing the visible light that enters your eye.
UV coatings can be applied to provide protection from the ultraviolet. Overexposure to the UV has been linked to such eye diseases as cataracts.