How To Choose Your Lenses

The most important part of a prescription is the lenses. It determines how comfortable you are with your  new glasses. There are so many options available on the market. This guide to eyeglass lenses will help you better understand what options are available to you and help you choose lenses and coatings to fit your preference and lifestyle.

After you choose your faviorate frame, you can click ADD LENSES button to select a pair of lenses for your frame.

Type of Lenses：

Single-Vision Distance

Single-vision distance lens is concave, or curve inward. If you have nearsightedness, you may be looking for single-vision distance lenses to correct your vision. Single-vision distance glasses prescription will begin with a (-).

Single-Vision Reading

Single-vision reading lens will be convex, or curve outward. Reading lenses are designed to help you see things at a close distance, typically between 30 and 40 cm. This lenses are suite for people with prescriptions beginning with a (+).

Progressive Lenses

Progressive lenses are no-line multifocal eyeglasses lens that have a seamless progression of added magnifying power for intermediate and near vision. The power of progressive lenses changes gradually from point to point on the lens surface, providing the correct lens power for seeing objects clearly at virtually any distance.

Bifocal Lenses

Bifocal lenses are the most common type of multifocal lens before the progressive lenses has been invented. There will be a visible line separating the 2 zones. The upper part of the lens is set for clear vision in the far distance, and the lower part is designed to correct your near vision.

This is a choice for people who use both distance and reading glasses, so they do not need to carry around two pairs of glasses wherever they go.

On VlookOptical.com you can choose different type of lenses after you click "Add Lenses" button.

Different Type of Materials：

Glass lenses. In the early days of vision correction, all eyeglass lenses were made of glass.

PROs：

• Better for Bifocals and Trifocals
• Clearer View
• Less Expansion and Contraction of Glass due to Extreme Temperatures
• May Offer Thinner Lenses than Plastic for Some People
• Scratch Resistant

CONs：

• Heavier than Plastic Lenses
• Break easily; potentially causing serious harm to the eye
• More Expensive than Plastic
• Not Recommended for Sports

Plastic lenses. In 1947, the Armorlite Lens Company in California introduced the first lightweight plastic eyeglass lenses. The lenses were made of a plastic polymer called CR-39, an abbreviation for "Columbia Resin 39," because it was the 39th formulation of a thermal-cured plastic developed by PPG Industries in the early 1940s.

Because of its light weight (about half the weight of glass), low cost and excellent optical qualities, CR-39 plastic remains a popular material for eyeglass lenses even today.

In the past 20 years, in response to the demand for thinner, lighter eyeglasses, a number of lens manufacturers have introduced high-index plastic lenses. These lenses are thinner and lighter than CR-39 plastic lenses because they have a higher index of refraction (see below) and may also have a lower specific gravity.

PROs:

• Better for Anti-reflective Coatings
• Lenses Can Be Tinted in Almost any Color
• Less Prone to Breaking or Cracking
• Lighter Than Glass
• UV Resistant

CONs:

• Not as Clear as Glass
• Scratch Easily
• Susceptible to Expansion and Contraction in Extreme Temperatures

Polycarbonate lenses. In the early 1970s, Gentex Corporation introduced the first polycarbonate lensesfor safety glasses. Later that decade and in the 1980s, polycarbonate lenses became increasing popular and remain so today.

A newer lightweight eyeglass lens material with similar impact-resistant properties as polycarbonate is called Trivex (PPG Industries), which was introduced for eyewear in 2001. A potential visual advantage of Trivex is its higher Abbe value (see below).

PROs:

• Strong; Hard to Breaking or Cracking
• Light
• Shatter-resistant 
• Excellent choice for young children or those involved in high-impact work or activities

CONs:

• Extremely scratch-prone
• High density causes a high amount of visual distortion and blurriness known as chromatic aberration.
• Less desirable for normal everyday wear

Lenses Index

The index of your lens, also referred to as the index of refraction. it pertains to optical lenses, discusses how efficiently a lens material can refract or bend light. The higher the refractive index of the lens, the more slowly light moves through it, and the more the light bends, That means the lens will become lighter and thinner.

If you have a particularly strong prescription, a lens with a higher index may be the best choice for you. At Vlook, we offer lesnse with index from 1.56 to 1.74.

the index of refraction as it pertains to optical lenses, discusses how efficiently a lens material can refract or bend light.  The higher the index of the material the more efficient it is as a refractive medium.  As the result of a material’s increased efficiency, a lens constructed of a higher index material can be made thinner and still achieve the same optical effect of a thicker 1.49 plastic lens.

1.50 Index Standard Lens for most

1.50 plastic lens is a common standard optical material for many optical store and online optical website. It Mainly used for prescriptions +/-3.00D. However, the disadvantages of 1.5 index lenses are too heavy and thick. Many online optical shops offer free 1.5 Index lens for free with their frames; however at Vlook, we do not offer 1.5 index plastic lenses anymore. We have fully upgraded to the 1.56 index lens for free with our frames.

1.56 Mid-index

This lens material is 15% thinner than regular plastic and moderately lighter and stronger. We recommend it can be used for prescriptions ranging from 0.00D. to +/-3.50D and CYL corrections of +/-3.00 and below. In this prescription ranges, 1.56 mid-index will be the best choice for you. 1.56 Mid-index single-vision lenses with Anti-scratch hard coating and Anti-Reflective coating come free with all Vlook frames. 

1.60 High Index

This lens index is a great option for people with moderately stronger prescriptions. It is up to 25% thinner than regular plastic and provides 100% UV protection in its naturally clear state. We recommend using this for prescriptions ranging from +/-3.50D. to +/-6.50D and CYL corrections of +/-3.00 and below.

1.67 MR-7 High Index — Ultra-Thin Lens

This lens material is great for people with strong prescriptions and still want have a thin and light eyewear. 1.67 High Index lens is 30% thinner and lighter than 1.50 index lens and provide 100% UV protection. We typically recommend these lenses for people with SPH corrections between +/-5.00 and +/-8.00, and CYL corrections between +/-3.25 and +/-4.00. In addition, this material is a good option for semi-rimless and drill mounted frames as it is less prone to chipping and cracking than regular plastic.

1.74 Ultra Hi-index Plastic

The thinnest lenses are designed for the highest-powered prescriptions. 1.74 ultra-high-index material can efficiently bend light. Resultingly, it is 50% thinner than 1.50 standard lens in same prescription and also provide 100% UV protection. It is the optimum choice for people with very strong prescriptions; best for prescriptions with SPH corrections of +/-6.50 and above, and CYL corrections between +/-4.25 and +/-6.00. This is also a perfect option for semi-rimless and drill mounted frames as it is less prone to chipping and cracking than regular plastic.

Abbe Value

The Abbe value (or Abbe number) of a lens material is an objective measure of how widely the lens disperses different wavelengths of light as light passes through it. Lens materials with a low Abbe value have high dispersion, which can cause noticeable chromatic aberration — an optical error visible as colored halos around objects, especially lights.

When present, chromatic aberration is most noticeable when looking through the periphery of eyeglass lenses. It is least noticeable when looking directly through the central optical zone of the lenses.

Abbe values of eyeglass lens materials range from a high of 59 (crown glass) to a low of 30 (polycarbonate). The lower the Abbe number, the more likely the lens material is to cause chromatic aberration.

Abbe number is named after the German physicist Ernst Abbe (1840-1905), who defined this useful measure of optical quality.