Tips for buying kids eyewear
“High-index” lenses are the right choice if you want thinner, lighter lenses and glasses that are as attractive and comfortable as possible.
The stronger the prescription, the thicker the edges.
Most of today’s fashionable frames are made of plastic or metal with rims thinner than the lens itself. Also, popular rimless mountings mean that the edges of the lenses are completely exposed. In either case, the lens edges are highly visible, and thicker edges can detract from the appearance of your eyewear.
Regular glass or plastic lenses for high amounts of nearsightedness or farsightedness can be quite thick and heavy. Fortunately, there are a variety of new “high-index” plastic lens materials that bend light more efficiently. This means less material can be used in high-index lenses to correct the same amount of refractive error, which makes high-index plastic lenses both thinner and lighter than conventional glass or plastic lenses.
Thinner, lighter high-index lenses are especially recommended if you have a strong prescription for nearsightedness, farsightedness or astigmatism.
Advantages of High-Index Lenses
Thinner. Because of their ability to bend light more efficiently, high-index lenses for nearsightedness have thinner edges than lenses with the same prescription power that are made of conventional plastic material.
Lighter. Thinner edges require less lens material, which reduces the overall weight of the lenses. Lenses made of high-index plastic are lighter than the same lenses made in conventional plastic, so they’re more comfortable to wear.
The most popular type of high-definition lenses are called free-form lenses. The term “free-form” refers to an advanced manufacturing process that reduces higher-order distortions that occur in lenses created with traditional lens manufacturing tools and processes.
High-definition lenses are designed to provide sharper vision in all conditions and reduced glare for night time driving.
With free-form lenses (also called digital high-definition lenses), the fabrication of the lenses from wearer’s glasses prescription is optimized, to provide the most accurate lens power and the sharpest vision possible.
The result is that high-definition lenses may provide sharper image quality, better peripheral vision, improved contrast and less glare at night.
Because of the sophisticated technology used to design and fabricate free-form and wavefront lenses and the added time and equipment required to fit them, expect to pay up to 25 to 30 percent more for high-definition glass lenses, compared with conventional lenses of the same material and design.
Though high-definition lenses cost more than conventional glass lenses, many people who try them — particularly wearers who’ve been frustrated by a lack of crisp vision with glasses in the past — find free-form and wavefront lenses produce a noticeable improvement in clarity and comfort
Why multifocal lenses? You may be maturing, but “mature” doesn’t have to mean “old.” If you are in your 40s (or older) and are having trouble reading fine print with your glasses, multifocal lenses offer a younger-looking appearance and other advantages over the lined bifocal lenses your parents wore.
Multifocal lenses eliminate the visible lines of traditional bifocals and hide the fact that you need reading glasses. With multifocal lenses, no one has to know whether you’re wearing glasses just for fashion — or because your arms have “grown too short” for you to see up close.
In addition to cosmetic advantages, progressive multifocal lenses provide a more natural correction of presbyopia than bifocal lenses.
Instead of having just two or three lens powers like bifocals or trifocals, multifocal lenses are true “multifocal” lenses that provide a seamless progression of many lens powers for all viewing distances.
With multifocal lenses, you can look up to see clearly across the room and in the distance. You also can look ahead to view your computer in the intermediate zone and drop your gaze downward to read and do fine work comfortably through the near zone of the lenses.
And it’s easy to adapt to today’s modern progressive lenses.
Progressive lenses are line-free multifocals that have a seamless progression of added magnifying power for intermediate and near vision.
A “corridor” of optimum lens power runs vertically down each progressive lens. Your optometrist will take careful measurements of your eyes and glass frame in order to place the corridor in just the right location so your eyes can naturally access the various powers within the lens for comfortable viewing at all distances.
And progressive lenses eliminate an annoying problem caused by bifocal and trifocal lenses known as “image jump.”
With conventional bifocals and trifocals, images seem to “jump” as your eyes move past the sharply defined boundary between the distance and near parts of the lens. With progressive lenses, the transition between lens powers within the lens is smooth and seamless, letting you change focus from distance to near and back again more comfortably, with no image jump.
Progressive lenses also are available in a wide variety of materials, including regular plastic, polycarbonate, high-index and photochromic lenses.