High Index Lenses

Should I Get High Index 1.74 Aspheric Lenses?

The benefits of 1.74 high index material and an aspheric cut can be combined to produce an exceptional set of lenses for your eyeglasses. To determine if they’re right for you and if you’ll get the most out of your investment, let’s review the characteristics of 1.74 high index lenses and the effects of aspheric lenses.

High Index 1.74 Aspheric Lenses

High index lenses allow for prescriptions to be cut using less physical material than conventional glass or plastic. This is particularly beneficial if you have a strong prescription, as high index produces lenses that are lighter and thinner than conventional ones. The “bug eyes” or “tiny eyes” effect will also be greatly reduced.

1.74 high index lenses are the thinnest and flattest lenses available in plastic. Weight is greatly reduced and although they cost significantly more than standard, 1.50 index lenses, they are 50% thinner. Even if you already use high index lenses, a step up to 1.74 can produce a noticeable improvement. A 1.74 lens is 13% thinner than a 1.67 lens.

Unlike conventionally-shaped lenses, which form a sphere, aspheric lenses taper out towards the ends to produce a flatter overall profile. This allows an aspheric lens to look better inside a frame, lacking the bulge and protruding ends of a standard lens. And because the surface is flatter than a spherical one it produces less distortion as your eyes move towards the edges of the lens. Aspheric lenses are best suited for minus prescriptions although a slighter reduction in thickness can still be perceived in a plus prescription.

As with high index material, the real benefits of aspheric lenses shine through when they are used to create stronger prescriptions. Due to the thicker, heavier lenses strong prescriptions require, typically frame styles and types are limited if you order your lenses in a standard glass or plastic format. Also, stronger prescriptions require greater curvature, and the thicker and more curved the lens, the greater the distortion.

To summarize, you’ll benefit most from 1.74 high index aspheric lenses if:

• Your prescription strength warrants a desire for thinner lenses.
• You want to increase your selection of available frames.
• You want to step up from conventional lenses, or improve the positive effects of 1.67 high index lenses.
• You will benefit from a reduction in lens weight (less slippage, indent marks on nose, etc.)
• You wish to reduce the distortive effects of your current lenses.