Lenses 

As technology advances, so do lenses. In the past, they were made exclusively of glass. Today, most are made of high-tech plastics. There are several types of lenses and lens coatings to choose from.  Lens coatings can enhance the durability, performance and appearance of your eyeglass lenses. When purchasing new eyeglasses, here are lens coatings and treatments you should consider.

Types of Lenses

Single-vision lens

Single-vision lenses usually offer visual correction for just one distance, be it for general distance vision, for a specific distance or for near vision. They are classified in spherical, aspherical, astigmatic and prismatic lenses.

Multifocal lenses

Multifocal lenses are lenses designed to provide two or more visibly divided portions of different focal powers. Multifocal lenses are Bifocals, Trifocals, or Progressive. 

Bifocal lenses

Bifocal lenses enable clear vision at two different distances, usually for near and distance vision. The upper part is designed for distance use and the lower part for reading. Bifocal lenses eliminate the need to swap between different pairs of glasses for different visual tasks.

Trifocal lenses

Trifocal lenses are multi-power lenses with three points of focus. Most have one zone for distance vision, one for intermediate vision and one for near vision. The intermediate zone usually provides 50% of the added magnifying power of the near zone.

Progressive lenses(no-line bifocal)

Unlike bifocals or trifocals, progressive lenses offer the right power for every distance. They allow smooth vision at any distance. Progressive lenses are roughly divided into three vision zones: distance zone, progression channel (intermediate zone) and near zone. The transition between these zones is smooth and invisible on the outside. The width of the progression channel depends on the design of the progressive lens and the power of the addition. The peripheral areas on the right and left-hand side of the progression channel limit the useable zones of the progressive lens.

Lens Materials

Polycarbonate

These impact-resistant lenses are thinner, lighter, and a good choice if you play sports, work where your eyeglasses could easily get damaged, or have kids who are tough on their specs. They also have built-in UV protection.

Trivex 

They’re made from a newer plastic that’s similar to polycarbonate lenses. They’re lightweight, thin, and impact-resistant. They may also correct vision better for some people.

High-index plastic

If you need a strong prescription, these lenses are lighter and thinner than the old-school super-thick ones you may have had in the past. High index makes it possible for you to achive the thinner lenses with your presrription.

Aspheric

These have various degrees of curvature. That means they can be thinner and flatter so you can use a much larger portion of the surface.

Lens Enhancements

Blue blocking filters

Standard light protection lenses evenly reduce the visible light across the entire spectrum. By contrast, blue blocking filters cut off a specific portion of the short wavelengths of light at a defined point in the light spectrum. This is why blue blocking filters considerably reduce glare and improve contrast vision. They are a great option for alot of computer use.

Anti-reflective

It can help with glare, reflections, halos around light, and make for a nicer look.

Scratch-resistant (TD2)

Most lenses today have these built in. No eyeglass lenses — not even glass lenses — are scratch-proof.

However, lenses that are treated front and back with a clear, scratch-resistant coating have a much harder surface that is more resistant to scratching. Kids' lenses, especially, benefit from a scratch-resistant hard coat for greater durability. 

Ultraviolet protection

Just as sunscreen keeps the sun's UV rays from harming your skin, UV-protective treatments for eyeglass lenses block those same rays from damaging your eyes.

Tinted lenses 

Available in a variety of colors to match your personal style or to enhance sight for specific activities with lenses fully tinted, graduated or given a mirror coating.Sometimes, a light or dark hint of color on the lens can help you see better. A yellow tint may increase contrast. A gray tint to your sunglasses won’t change the colors of things. A light tint can hide signs of aging around your eyes. You would also use tint for sunglasses

Mirror coatings

This is purely for looks, but it does hide your eyes from view. You can find them in a range of colors like silver, gold, and blue.

Photochromic

Sunlight changes these from clear to tinted. You may no longer need sunglasses, although some may not darken in your car if the windshield blocks UV rays. Some photochromic lenses to activate with both UV and visible light, providing some darkening behind the windshield. Some photochromics are fully clear indoors and darken outdoors, variable polarization, and extra dark outdoors with a hint of tint indoors to protect against harsh indoor lighting.

Polarized

(Sunglasses) These lenses reduce glare from a surface like water, so they’re great for sports and driving.Polarized sunglasses have been popular for years with boaters and fishermen who need to reduce reflected glare from the water surrounding them. But now that many others who spend time outdoors have discovered the benefits of polarized lenses.

Polished edges

Make the edges of your lenses appear clearer, thinner and less visible.