The refractive index describes how strongly a material bends light. Higher-index materials need less thickness to reach the same power, so strong prescriptions can be thinner and lighter.
| Index | Material | Often suggested for* |
|---|---|---|
| 1.50 | Standard plastic (CR-39) | Low prescriptions, approx. up to ±2.00 |
| 1.59 | Polycarbonate | Kids, sport and rimless frames; impact resistant |
| 1.61 | Mid-index | Moderate prescriptions, approx. ±2.00 to ±4.00 |
| 1.67 | High-index | Stronger prescriptions, approx. ±4.00 to ±6.00 |
| 1.74 | Ultra high-index | Very strong prescriptions, approx. beyond ±6.00 |
*Ranges are general guidance used for suitability notes in our lens builder, not clinical recommendations. Your eye-care professional can advise what suits your prescription.
Frame choice matters too
Smaller, rounder, full-rim frames keep strong lenses slimmer. See best frames for high prescriptions.
