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Lens Index Guide: What Is the Best for You?

Most people are aware that a higher prescription typically means thicker lenses. If you need a strong prescription to see clearly, you would have no choice but to wear thicker lenses, but that was before. Lens technology has evolved a lot in recent years and now, even those who require higher prescriptions can still wear thinner lenses, which are much lighter and more comfortable. All that’s needed is to choose a better lens index.

 

eyeglasses lenses

What Is Lens Index?

The lens index is a range of numbers that denote the thickness of a lens, with the number being inversely proportional to the thickness. That is, the higher the lens index number, the thinner the lens.

As prescription strength gets higher, the lenses have a tendency to become a lot thicker. To save people from the burden of wearing cumbersome eyeglasses, a higher lens index is usually applied to stronger prescriptions. This keeps the lens relatively thin despite the high prescription.

 

Common Types of Eyeglasses Lens Index

Lens Index Chart

The lens index number for eyeglasses ranges from 1.5, which is the thickness of regular lenses, all the way to 1.9, which are the thinnest lenses available today. Of these numbers, there are four that stand out as they are the most commonly chosen by wearers of eyeglasses, and these are available at BlueLightPC:

1.56 Standard Lenses

1.56 index standard lenses are suitable for prescriptions of SPH +/- 2.50 and less (CYL +/-2.00 and less), and can be fitted into any kind of frame.

1.61 Popular Lenses

The 1.61 lenses are a popular choice among people who have a prescription strength from SPH +/-2.00 to +/-4.50 (CYL +/-4.00 and less). These lenses are approximately 20% thinner than the standard 1.5 index, and are best for full-rim and semi-rim frames.

1.67 Thin Lenses

For much stronger prescriptions like those that range from SPH +/-4.50 to +/-7.00 (CYL +/-4.00 and less), you can choose the 1.67 index lenses of BlueLightPC.

1.74 Thinner Lenses

These high-index lenses are the thinnest and lightest lenses that are easily available from most optical shops. 1.74 lenses are thinner and more lightweight than 1.67 lenses, and are recommended for strong prescriptions of SPH +/-6.50 or higher (CYL +/-6.00 and less).

 

Higher levels of customization are also available. If your prescription falls outside of the above ranges, you can email BlueLightPC and we can customize a pair of glasses to your prescription.

 

Why Are High Index Lenses More Expensive?

The higher the lens index, the more expensive it costs. Why is this so? In general, the higher your prescription is, the thicker the lens is. In order to keep the lens thinner for aesthetic, high index lenses were created. And this requires more advanced lens design and manufacturing techniques, so the cost increases.

Many wearers feel that the cost is worth it because, in addition to being thinner and lighter, high-index lenses are also more flattering to wear.

 

How to Choose the Right Lens Index?

The first criterion to consider in order to choose the right lens index is your prescription. As you can see from above, the various lens indexes are suitable for a specific range of prescription strength. While getting checked, you can ask your eye doctor what they think should be the appropriate lens index for your particular prescription.

For most prescriptions, people actually have no problem wearing glasses with a 1.56 lens index, particularly if their prescriptions are not that high anyway. Some don't even mind the thick lenses as the prescription gets higher. But if you want to wear a thinner and more comfortable lens, then high-index lenses are a great option.

Take note that the higher index lenses might not work for certain frame types, like rimless or semi-rimmed glasses. Very thin lenses can be extremely delicate and must only be fitted into full-rim glasses for safety.