Do you feel overwhelmed when picking eyeglass lenses? There are glass lenses, nylon lenses, resin lenses, plus lenses with refractive indices of 1.56, 1.61 and 1.67. How do you make the right choice?
Lens Materials
1. Glass Lenses
Made primarily of optical glass, they feature excellent optical properties and a high refractive index. A higher refractive index means a thinner lens. However, glass lenses are fragile and relatively heavy. For daily use, they are cumbersome to wear and easy to break, so they are not widely used nowadays.
2. PVC Plastic Lenses
PVC is a type of thermoplastic material. Solid PVC is heated and molded into lenses. Such lenses are low-cost, but they have poor light transmittance, low heat resistance and are prone to deformation. They are mostly used for decorative glasses. Despite the low price, PVC lenses are not recommended for long-term daily wear.
3. Nylon Lenses
Nylon lenses are made of transparent polyamide. Thanks to its special physical properties, the material was initially applied to spacesuit visors, police and military anti-explosion gear, and precision instruments. Due to the high cost, civilian nylon lenses are mainly used for professional sports protective eyewear and luxury sunglasses. They come with a hefty price tag for ordinary consumers, while they are a casual pick for the wealthy.
Note: Many cheap lenses on the market claim to be nylon products. They are actually made of common polyamide, which looks similar but is not genuine nylon material.
4. Resin Lenses
Resin lenses are optical lenses made from resin, available in coated and uncoated versions. They are lightweight, impact-resistant and deliver good light transmission. Coated resin lenses see great improvements in waterproof performance and wear resistance. Additional functional coatings can also be applied to provide UV protection, blue light blocking and photochromic effects.
Today, resin lenses account for 99% of all lenses sold in optical shops. Basic uncoated resin lenses are also known as “white lenses” at a low price. The price of coated resin lenses varies according to coating techniques and additional functions.
Spherical vs. Aspherical Lenses: Which Is Better?
The two types differ in surface curvature. Traditional spherical lenses cause severe aberration and distortion, leading to blurry vision, distorted views and a narrow field of vision.
Aspherical lenses correct these flaws effectively. Meanwhile, they are lighter, thinner and more stylish.
Advantages of Aspherical Lenses
Sharper vision: With professional coatings, they deliver clear and comfortable visual experience.
Lightweight to wear: You can barely feel the lenses on your eyes.
Natural view: They minimize visual distortion and present realistic scenes.
Given people’s pursuit of life quality and appearance nowadays, aspherical lenses are highly recommended for their light weight, thin profile and attractive look.
Lens Refractive Index
The numbers 1.56, 1.61 and 1.67 stand for lens refractive index, a core parameter of eyeglass lenses.
Differences Between 1.56, 1.61 and 1.67 Lenses
For lenses of the same material and power, a higher refractive index results in a thinner lens. Lenses with a higher refractive index cost more to produce and process, so the larger the number, the higher the price.
Under the same material, power and curvature design, a 1.56 lens is thicker than 1.61 and 1.67 lenses. For people with high myopia, high-index lenses reduce overall weight and look more appealing. Besides, aspherical lenses are thinner than spherical ones even with the same refractive index.
For most people, coated aspherical resin lenses are the top choice, as the technology is mature, the price is reasonable and they are comfortable to wear. Luxury lenses are an option for those with a higher budget.
Guidance on Choosing Refractive Index
Below 200 degrees of myopia: Choose 1.56
200 to 400 degrees of myopia: Choose 1.61
Over 500 degrees of myopia: Choose 1.67
After going through the above classification and comparison, you will have a basic understanding of lenses. Next time you visit an optical shop, you can select suitable lenses based on your own needs and avoid unnecessary spending.
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