Have you ever seen people wearing glasses with lenses so thick they make the wearer's eyes look bigger?
Fortunately, with improvements in lens technology, you can now order lenses in higher indexes, which are thinner and lighter than regular lenses.
With high-index lenses, you can wear thin, lightweight glasses without feeling self-conscious about your lenses protruding from the frame if you have a high prescription.
You can refer to our table below to find out whether you should consider high-index lenses.
Lens Index Chart
| SPH (your degree) | Recommended Lens Index |
| 0.00 to -3.00 | 1.50 or 1.56 |
| -3.25 to -6.00 | 1.60 |
| -5.25 to -8.00 | 1.67 |
| -8.25 onwards | 1.74 |
Common Questions
1. Are high-index lenses worth getting?
If you have a high prescription but don't want thick lenses, high-index lenses are worth the investment because they are the thinnest lenses for high prescriptions.
High-index lenses are also a great option if you wear glasses while playing sports because regular lenses, which will be thicker and heavier, may cause your glasses to slide off your face.
2. Is a higher index better?
You should only opt for a higher index lens if you have a high prescription.
If you have a lower prescription, a regular 1.50 index lens will be just as thin and light as a 1.67 high-index lens edged to a higher prescription.
In fact, some optical labs are unable to edge 1.67 high-index lenses for prescriptions weaker than -2.
3. What is the difference between 1.67 and 1.74 high index lenses?
In technical terms, 1.67 high-index lenses bend light at a refractive index of 1.67, whereas 1.74 high-index lenses do so at an index of 1.74.
In practical terms, 1.74 high-index lenses are up to 10% thinner and lighter than 1.67 high-index lenses but cost up to 4 times more than the latter.
Conclusion
If your prescription is -3.00 or higher (e.g. -3.25, 5.00 etc.), consider high-index lenses because they will be thinner and lighter than regular 1.50 index lenses.
However, if you have a low prescription, regular 1.50 index lenses will be just fine for you.
If you have any questions about lens indexes, you can always approach an optometrist for advice.