https://www.thevisioncouncil.org/content/lens-materials/teens
https://www.zennioptical.com/blog/get-thinnest-lenses-prescription/
High-Index Plastic
Benefits: Thinner, lightweight lens for stronger prescriptions
Eyeglass wearers are no longer limited to thick, heavy glasses. High-index plastic lenses are slim and sleek, providing an alternative option for strong prescriptions.
High-index lenses are typically more expensive than standard plastic and mid-index varieties, but offer a wider choice of frames for people with stronger prescriptions, since the lenses are not bulky. Wearers benefit from a crisp, clear field of vision and comfort, even during prolonged use. When treated with a no-glare coating, high-index lenses sharpen sight considerably—especially at night.
Definition (HD)
Benefits: Digitally customized lenses for all prescriptions
HD, or digital lenses as they are also referred to, have been described as the most important improvement in prescription eyewear in the last 100 years. The improvement wearers see in moving from traditional lenses to digital lenses has been compared to the difference in using an old, analog television compared to a new high-definition television, or an early cell phone to today’s digital smart phones. A recent study by the University of California at Berkeley confirmed consumer preference for HD lenses over conventional progressive lenses, in part because they reported being able to adapt faster to using the lenses and a wider field of vision when viewing objects nearby.
Unlike traditional lenses, HD lenses are manufactured using digital computer technology and diamond-cutting tools that allow the lenses’ surface to be customized to an individual’s eyes. High-definition lenses can deliver this unprecedented level of customized vision correction because the lenses are engineered based on a digital scan of the eyes. The resulting, customized vision correction improves unique vision problem areas and providers wearers with superior clarity, and sharper, brighter eyesight, whether they are nearsighted, farsighted, or have a mild astigmatism. The lenses are also thin and light, making them ideal for long wear, even with the strongest prescriptions. HD lenses are most common in progressive lenses, but they can also be made for single vision glasses. Most teens do not need HD glasses, as they are usually for progressives, but premium glasses can be made after a specialized eye exam.
This handy online tool is the Lens Thickness Calculator. It can be found here, at the OptiCampus website.
1) Your prescription. This you cannot change to get a thinner lens. Doing so would be counterproductive, in that you would not be able to see well if you take it upon yourself to lower your prescription below what your eye doctor has prescribed.
In addition, prescriptions with astigmatism corrections – if you have this, there will be numbers in the Cylinder (CYL) and Axis(sometimes abbreviated X) fields – generally result in thicker lenses than those without astigmatism corrections.
2) Your lens index. The lens “index” is short for the lens’s “index of refraction.” That means how much the lens bends the light that enters it. That’s what refraction is. Bending the light focuses it right into the middle of your visual sweet spot, the retina, so you can see well.
You can change the index to thin the lens, up to a point. After that point, the law of diminishing returns kicks in. The lens that is recommended for your prescription will be the thinnest lens. Choosing a lens index that’s higher than the recommended lens index won’t make the lens thinner, and you’ll end up paying more for no improved result.
3) Your lens width. This can have a considerable effect on your lens thinness. Once you have settled on the correct lens index, having determined that going to a higher lens index number won’t result in a thinner lens, the lens width – also known, weirdly, as the “eye size” – will be the last, and in some situations, the most important – factor in thinning your lens.
Scratch and impact resistance. Polycarbonate lenses are treated with a special hard coating that make them more resistant to scratches and impact. This is especially helpful for those that get a lot of wear and tear on their glasses, people working in jobs at high risk for an eye injury, and children.
UV protection. Polycarbonate material naturally blocks UV light. This helps protect your eyes from the sun’s harmful rays
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