Best Lens Materials for Glasses

by Jul 5, 2023

Glasses, also known as eyeglasses, spectacles, or simply specs, have been around for centuries, helping people see better. They consist of a frame that holds two lenses which are mounted in such a way as to correct your eyesight. However, the lens material they are made of can vary greatly. In the past, glass was the only material available to make lenses. As technology advanced and knowledge of optics grew, the materials used to make lenses evolved.

Today, a wide variety of materials are available, and it is very uncommon to find lenses made from glass. Instead, a variety of plastics are utilized for prescription lenses, which are more lightweight, less fragile, and easier to manipulate. There are many factors that determine which lens material is best for your glasses, and the decision-making process is often done in consultation with your optometrist or optician.


Common Lens Material in Glasses

Some of the most common lens materials are CR-39 plastic, Polycarbonate plastic, and 1.67 High Index plastic. Each of these materials has advantages and is the most desirable in certain circumstances.


CR-39 Plastic

The CR-39 plastic was one of the first plastics to be used in eyewear, and it continues to be a popular choice of material due to its affordability. It has a good lens material profile with an index of refraction of 1.52 and a specific gravity of 1.32. It is also easy to tint and manipulate into frames.

CR-39 is an ideal option if you have a low plus or minus prescription and do not require additional protection from your lenses. However, if you are looking for impact resistance, you may want to consider other options.


Polycarbonate Plastic

Polycarbonate plastic is a popular material for glasses because of its high level of impact resistance. It has an index of refraction of 1.586 and a specific gravity of 1.20, making lenses thinner and lighter than CR-39 while maintaining good optical quality. Polycarbonate is considered the best choice for safety glasses and is also a good option for children’s glasses.


1.67 High Index Plastic

1.67 high-index plastic is an ideal option if you have a high prescription, as it is the thinnest option available for lenses. It is a slightly more expensive option than CR-39 or polycarbonate, but it provides exceptional optical performance due to its index of refraction of 1.67. It has a specific gravity of 1.37, which means the lenses are moderately heavy, but not as heavy as other high-index materials. While it provides thinner lenses than the other two materials when you have very high prescriptions, the reduction in thickness usually comes with an increase in costs.


Factors in Choosing Lens Materials

Two important factors that help determine the best material to use for your lenses are an index of refraction and specific gravity. The index of refraction determines how thick a lens needs to be to provide the needed prescription; the higher the index of a material, the thinner the lenses can be made. The specific gravity determines the weight of the lenses made from the material. The higher the value of specific gravity, the heavier the lenses made from the material are. Additionally, impact resistance, ability to be tinted, and cost of the material also play a role in determining the best material for you.


Be Sure to Consult Your Optometrist or Optician

It is essential to consult with your optometrist or optician to decide on the best lens material for your glasses. Your optometrist or optician has the knowledge, expertise, and tools to help you choose the appropriate material based on your visual needs, prescription, frame choice, and lifestyle. They will also consider other factors like your occupation, hobbies, budget, and the level of protection you may need.


Our eye doctors at Wilmington Family Eye Care in Wilmington, DE excel in the prescription of glasses, contact lenses and the diagnosis of a variety of eye diseases. Call our optometrists at 302-299-1286 or schedule an eye exam appointment online if you would like to learn more about the best lens materials for glasses. Our eye doctors, Drs. Daniel Baruffi, Amy Quan, Patricia Jones, and Joseph Goldberg provide the highest quality optometry services and eye exams in Wilmington, Delaware, and its surrounding areas.


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