High Index Eyeglasses: Lightweight and Comfortable
A high lens prescription doesn’t mean resigning yourself to glasses with thick and heavy lenses. The thickness and weight of high corrective lenses have dropped considerably thanks to improved lens material technology and better lens making techniques. The improved lenses, called “high index lenses” use materials that bend light at a greater angle. That is, they have a higher index of refraction. This means a thin and lightweight high index lens will do the same job as a much thicker and heavier strong prescription lens made of standard lens materials.
If style and personal appearance are important to you, then it’s clear that high index eyeglasses are the way to go. Not only do the thin lenses look better, they allow more frame options for expressing personal style.
Suppose for the sake of argument, that appearance and style aren’t that important to you. Should you save money with thick lenses made from a standard lens material such as CR-39? Probably not. A good practical reason in favor of high index lenses is their light weight. Heavy lenses cause two problems with important consequences:
Heavy Eye-wear Can Slide down Your Nose
The heaviest part of your glasses sits on the bridge of your nose. If your frame sizing isn’t perfect and the lenses are too heavy, they can slide down your nose. This is especially a problem when making sudden movements, looking down at the ground, or when engaged in a repetitive impact activity such as running. Heavy lenses also require more friction to stay in place. Perspiration from hot weather or physical activity acts as a lubricant, which increases the likelihood of heavy glasses sliding down your nose.
Is this really a problem? Yes. Beyond the annoyance factor, your glasses are more likely to fall off your face. This means there’s an increased risk of scratches each time they fall to the ground. If this happens while walking on carpeting or your lawn, then you’re in luck. But if the glasses land on concrete or pavement, you’ll have yet another set of scratches on your lenses. In some circumstances, you or someone else may accidentally step on your glasses, or they may fall into an inaccessible place.
Another problem is that your glasses won’t properly correct your vision if they aren’t positioned on the bridge of your nose where they belong. When they’re further down the nose, the vision correction is less accurate. In addition, the glasses are located farther away from your eyes. This reduces your field of view through them.
Heavy Eye-wear Is Uncomfortable
Discomfort is essentially low-grade pain. At the very least, it’s distracting. At the worst, it can diminish your quality of life. If your glasses are sliding down your nose, you may try dealing with the problem with an excessively tight fit at the temple arms or the nose pads. Tight arms cause pain near the ears as well as headaches. An overly tight nose pad causes painful skin indentations. Even if your glasses don’t slide down your nose, the excessive weight of thick lenses is enough to cause indentation and pain.
Of course, glasses with a poor fit can cause both of the previously discussed problems regardless of the lens weight. Temple arms that are too long will cause the glasses to slide down your nose. When they’re too short, the nose pads can press painfully into your nose bridge.
The same is true of the bridge size of your glasses. This is the distance between the two lenses. A bridge size that’s too short causes painful pinching at the nose, while one that’s too wide will cause the glasses to slide down. However, glasses weighed down with thick and heavy lenses make the problem of finding the right frames more difficult. A good and comfortable fit is much easier to achieve when using thin and lightweight high index lenses.