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What is the difference between high index and polycarbonate lenses?
Wiki User
∙ 9y ago
High-index lenses are an alternative choice to standard, plastic eyeglass lenses. Although high-index lenses are more expensive than plastic lenses, they can reduce the thickness and weight of an eyeglass lens, particularly for individuals with a strong prescription.
High-index lenses are able to bend light to a stronger degree than a lens with a lower index, therefore the higher the index of the lens the less material needed to achieve a given prescription.
High index lenses are categorized according to how strongly they bend light. The higher the index, 1.53 to 1.74 for high-index lenses, the better the lens is at bending light.
High index lenses are 20 percent to 65 percent thinner than standard plastic lenses. In general, the stronger the prescription, the greater the difference in thickness between standard plastic and high-index plastic.
A reduction in lens thickness and weight will occur in high-index lenses for prescriptions stronger than +2.00 or -2.50. Weaker prescriptions are not thinner than standard lenses when made with high-index materials.
Polycarbonate lenses offer the same aesthetic benefits as high-index lenses, but polycarbonate lenses scratch easier, are difficult to coat or tint and are more likely to create distortions in colors and vision.
Wiki User
∙ 9y ago
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What is the difference between 1.50 standard and 1.57 mid index lenses?
Standard index 1.5 lenses Standard index 1.5 lenses are the basic CR-39 lenses, come with anti-scratch hard coating, and are shatter-resistant, suitable for spherical power +/- 2.00 or below, and cylindrical power +/- 1.50 or below. Index 1.57 mid index spherical lenses Index 1.57 spherical lenses are with anti-scratch hard coating. This higher index lens greatly reduces the thickness of the lens edge. This is suitable for spherical power of +/- 4.00 or below with cylindrical power +/- 2.00 or below. Index 1.57 mid index aspherical lenses Index 1.57 aspherical lenses are even thinner and lighter than 1.57 spherical lenses. These lenses come with anti-scratch and anti-reflective coating, greatly reducing the image distortion, suitable for spherical power of +/- 4.00 or below, and cylindrical power of +/- 2.00 or below. High index would be anything greater than the 1.57 lenses, like 1.61 or 1.67 and so on. Each having a degree of benefits and drawbacks unique to it's making.
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What is a 1.57 mid index single vision lens?
1.57 mid index single vision lenses means that the lens is thinner than standard plastic lenses. It is not the thinnest possible, nor is it impact resistant like Trivex 1.53 mid index lenses, or polycarbonate. It will be thinner than either of those materials. Single vision means that there is one range of vision. If a bifocal lens is not prescribed, then this is what the vision is. When the prescription is a bifocal prescription, then either distance only or reading only must be chosen.
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