Key Takeaways
- Lens index describes how much a lens bends light. A higher number means a thinner lens.
- Prescriptions around +/-4.00 and stronger tend to see a bigger difference in thickness.
- 1.61 and 1.67 suit moderate to strong prescriptions, while 1.74 fits +/-8.00 and higher.
- High-index lenses weigh less and fit more frame styles, though they cost more and offer less impact resistance.
- An anti-reflective coating can help counteract any extra reflections produced by high-index material.
High Index Glasses Allow for Thinner Glasses
High-index lenses are made from a plastic that bends light more efficiently. This allows for thinner lenses that provide the same degree of vision correction. Our optical team at Eyestyle Eyecare can walk you through whether high-index lenses are a good option for your prescription during your next comprehensive eye exam.
What High-Index Lenses Are
The index number on a lens tells you how well the material bends light. Standard lenses sit at the low end. As the number climbs, less material is needed to do the same job, which is why a 1.67 lens looks slimmer than a 1.50 lens with an identical prescription. High-index lenses are made from a plastic that’s designed expressly to keep them slim.
Why Some Lenses Turn Out Thick
Three factors contribute to lens thickness. The strength of your prescription is the main one, since more correction means more material. If you have astigmatism correction, this will also make your lenses thicker. Finally, the size of your lenses also contributes, with larger lenses generally being thicker.
Which Prescriptions Benefit from Thinner Lenses
If your prescription sits around +/-4.00 or stronger, thinner lenses are worth considering. That applies whether you’re nearsighted, farsighted, correcting astigmatism, or wearing progressives for presbyopia.
With a mild prescription, you may not notice much difference at all. Standard plastic is thin enough that thinner lenses won’t change how your glasses look or feel on your face.
1.61 vs 1.67 vs 1.74 Lenses
1.61 and 1.67 Lenses
These two cover moderate to strong prescriptions and handle the bulk of high-index requests. Next to standard plastic, the edges of these lenses look noticeably slimmer.
1.74 Lenses
For prescriptions at +/-8.00 and higher, 1.74 gives you up to 10% more thinness than 1.67. However, the material itself costs more to produce, and the price reflects this reality.
How High-Index Compares to Polycarbonate
Polycarbonate sits at 1.59, just under the high-index range. It also holds up better to impact, which makes it a practical pick for sports or active kids, but it won’t get as thin as 1.67 or 1.74.
Benefits & Trade-Offs of High-Index Lenses
What You Gain
Lighter lenses put less pressure on your nose and ears, which helps your glasses stay in place. They also reduce the way that strong prescriptions seem to magnify or shrink your eye.
What to Keep in Mind
Here’s what to weigh before you decide:
- High-index materials offer less impact resistance, so polycarbonate may suit sports and children’s glasses better.
- The price runs higher than standard lenses.
- The surface of high-index lenses reflects more light, and an anti-reflective coating may be needed to reduce glare and reflections.
Optometrists in Surrey and Kelowna
Thin lenses and a frame you like aren’t mutually exclusive. Book your appointment with our team at Eyestyle Eyecare in South Surrey or Kelowna, and bring along the style you’ve been eyeing.
