High Index Lenses

Do I Really Need to Get Ultra-Thin High Index Lenses?

High index lenses can greatly benefit corrective eye-wear wearers who require a certain prescription range – namely, a mid-level to high prescription, in terms of the measure of corrective strength.

Do I Really Need to Get Ultra-Thin High Index Lenses?

This is because stronger prescriptions require that longer, deeper curves be cut into your lenses, and the more curve you require, the thicker the lens material will need to be in order to accommodate that curve.

When using standard glass or plastic to form a strong prescription, lenses can become very thick and heavy. High index material is a composite made of either glass or plastic that allows for the use of less physical material when cutting those longer, deeper curves. As a result, a prescription cut into high index material can produce lenses that are significantly thinner and lighter than identical ones formed from standard plastic or glass.

But are the benefits of this worth it? Only you can determine that… but here are a few questions to consider when it comes time to decide.

• Are your standard-material lenses prohibitively thick?
• Do they distort the look of your eyes?
• Is weight a problem with your old lenses?
• Is cost a factor for you?
• Will the negative aspects of high index lenses pose a problem?

Lenses that are prohibitively thick cause both aesthetic and practical issues. They can stick out from behind your frames, especially at the edges, making it look as if you’re wearing goggles. They can also affect the frame style you choose. Certain frame styles, like rimless, semi-rimless, and some wire frames, are off limits to thick lenses because they simply cannot physically support the lenses.

Distortion is also a deciding factor. Thick lenses tend to magnify the look of your eyes. Depending on your prescription, they can make your eyes seem either too small or too large for your face. The stronger your prescription, the thicker the lenses, and the more out of proportion this magnification effect becomes.

Weight can also be problematic. Exceptionally strong prescriptions may result in lenses that weigh quite a bit. This limits the selection of frames in which you can mount them, and causes issues like indentations in your nose and constant slippage of the frame. Note that if your high index lenses are made of glass, they’ll be thinner than standard-material glass but may not be much lighter. Plastic high index lenses, however, generally offer a very noticeable reduction in lens weight.

The benefits of high index lenses come at a price. They cost more to produce than standard-material lenses, and depending on which high index rating you chose, that cost can be significant. If you’re on a tight budget and the cost of your eye-wear lenses is not covered by insurance, you may choose to forego high index lenses for now.

Finally, you need to be aware of the disadvantages of high index lenses. Abbe value, for instance; high index lenses have a lower Abbe rating than identical prescriptions formed from standard material, so while the thinner, lighter high index lenses offer cosmetic benefits, they do not surpass traditional lenses in vision quality. High index lenses can also be more brittle (especially in a glass format) and are more reflective than standard materials. Because of the latter, an anti-glare coating is strongly recommended with the purchase of high index lenses.

Take all these factors into account to determine if, in your particular situation, the advantages offered by high index lenses outweigh the disadvantages.