Several types of coatings can be added/layered to/on the lens to provide you with better comfort: no-glare, scratch resistance, antistatic, anti-smudge:
No-glare or anti-reflective coatings are layers of metal oxides applied to the lens to reduce undesired reflections, enhance appearance and increase transparency for better clarity of vision.
Smudges stay on ordinary lenses, but not on lenses with a no-glare treatment. Smudge resistant attributes help your lenses stay cleaner longer. The lenses wipe away fingerprints, dirt and oil while improving your visual acuity, the ability to see objects clearly.
Lenses that repel dust and dirt help you see clearly throughout the day. These low maintenance lenses reduce blurry, hazy vision.
All materials currently used in the making of optical lenses are subject to scratching. However, clear coatings are used to help lenses be more resistant. The plastic materials that are widely used today usually come with a built-in scratch-resistant coating. Scratch resistant coating increase the durability of your lenses.
Ultraviolet protection coating on optical lenses keep the sun's harmful UVs out, and diminish the risks of developing retinal damage and other serious eye conditions such as cataracts.
SPECTICAL LENS DESIGNS
Single vision lenses have the same optical focal point or correction over the entire area of the lens. Most non-presbyopic wearers will need single vision lenses to answer their visual needs. As a solution for presbyopia, single vision lenses only correct near vision. To see things far away, you need to remove your glasses or look over them.
Progressive lenses provide a smooth transition from distance to near vision, allowing the viewing of all intermediate distances. Progressive lenses are the optimum solution for presbyopia. These are designed to restore clear and accurate vision at all distances, without needing to constantly change glasses. The upper part of the lens makes it possible to see things far away, the central part to see the middle distance and the lower part to see close up.
Bifocal lenses usually have a straight or visible line that defines separation of the top area which is for distance vision and the bottom area reserved for reading. There are some round designs available however the straight top bifocal lens is most popular. The trifocal lens has three focal distances. The third focal distance, placed in the middle of the lens, is utilized for viewing intermediate distances that are not covered by the top or bottom sections.