Lens Thickness

Prescription Lens Index

In short, the refractive index or lens index determines how effectively a material is able to bend light. This number also describes how thick or thin your lenses are going to be. Typically, lenses with a high index will be thinner and are great for high prescriptions. Meanwhile, a low index lens material is geared for lower prescriptions as they will become thick as the diopter power increases.

What's the Difference?

Prescriptions are typically compatible with multiple lens indices. In most cases, it's really up to you to decide which one best suits your vision requirements and lifestyle.

There are some factors to keep in mind to help you in making your decision. A lower index is affordable but as the prescription gets higher the lenses get significantly thicker. A low index lens will also have more lens distortion at the edges as prescriptions get higher.

Meanwhile, a high index lens is lightweight and will be thinner on high prescriptions (better aesthetics). In terms of vision, a high index lens performs better than low index lens and will give you better visual acuity especially in higher prescriptions.

Cheat Sheet

High Prescription=High-Index

Prescription is higher than +2.00 to -2.00

Low Prescription=Low-Index

Prescription is lower than +2.00 to -2.00