All About Lenses
A visit to your eye care provider can uncover some confusing terminology about lenses. What do they mean? Are these lenses and coatings important for your vision or eye health? This is an overview of the more common lens options.
Anti-reflective Lens Coatings
An Anti-reflective (AR) coating is a type of optical coating (thin layer of material) that is deposited on an eyeglass lens to reduce the amount of glare and reflected light. Anti-reflective lenses:
- Improve night vision – reflections of streetlamps and headlights on your lenses are drastically minimized
- Decrease computer glare
- Reduce eye strain
- Lessen overhead fluorescent glare
High-index lenses are useful for people with stronger prescriptions. The thinner, lighter material is more comfortable and opens up a greater variety of frame options. However, they are more expensive than other lens options.
As we get older, our eye lens naturally thickens and becomes less flexible, leading to a vision problem called presbyopia. Multifocal eyeglass lenses contain two or more lens powers to help you see objects at all distances after you lose the ability to naturally change the focus of your eyes due to age (presbyopia). Here are a few multifocal lens solutions to consider:
Bifocals are lenses with two parts of different refracting powers, the upper for distance and the lower for near vision. There is a visible line distinguishing between the lower part – which can be a variety of shapes – and the rest of the lens.
Trifocals are lenses with three parts of different refracting powers: the upper for distance, the middle for intermediate, and the lower for near vision. There are clear lines of distinction for each range.
Progressive power lenses are true “multifocal” lenses like bifocals or trifocals, but they provide a lineless, seamless progression of varied lens powers for different distances. Wearers can look up to see clearly into the distance, straight ahead to view objects closer, like a computer, and then down to read or do close-up work.
Your eye care provider should measure your eye carefully to make sure they are putting the gradation of “zones” in the right place. Be aware that some people may need a short adaptation period to become fully comfortable using the lenses.
These lenses are clear indoors, but darken as a reaction to the UV rays in sunlight. They protect your eyes from 100% of the sun’s ultraviolet radiation, and can come in a variety of lens materials. Photochromic lenses offer the user the benefits of ‘regular’ glasses and sunglasses wrapped in one product.
Plastic lenses are light weight compared to glass, making them less likely to slip down your nose, especially in stronger prescriptions (stronger prescriptions tend to have thicker lenses). Plastic lenses are impact resistant, making them a better choice for children, active adults, sportswear, and safety wear. Plastic lenses are more likely to dent or crack rather than shatter the way glass does.
Polarized sunglass lenses are different than standard sunglasses in that they have a special filter within the lens that reduces glare. When sunlight hits off of a surface – particularly a smooth flat surface – the reflection can be amazingly bright. Polarized lenses are better at blocking this reflected light, making them an especially good solution for reducing glare while you do activities such as driving, boating, skiing, and fishing.
Polycarbonate lenses are the most-used alternative material for modern lenses. They are impact-resistant, lighter, provide 100 percent UV protection, are scratch resistant, and are easy to clean.They are great for sports protective eyewear and for kids.
Scratch Resistant Coating
Scratch Resistant Coating provides a much harder surface that is more resistant to scratching. Kids' lenses, especially, benefit from a scratch-resistant hard coat. Today, most eyeglass lenses have a built-in scratch-resistant coating;however, the coating can also be optional. Be sure to ask your eye care provider if scratch resistant coating is included with your lenses or to add it in if it is an optional feature you would like to have.
UV coating is a lens treatment consisting of an invisible dye that blocks ultraviolet (UV) light. Regular plastic eyeglass lenses block most UV light, but adding a UV-blocking dye boosts UV protection to 100 percent for added safety. Other eyeglass lens materials, including polycarbonate, most high-index plastics, and Photochromic lenses have 100 percent UV protection built-in, so an extra lens treatment is not required for these lenses.