Quick Answer
Higher refractive index = thinner, lighter lenses at the same prescription power.
Index Guide
| Index | Best For (SPH) | Weight / Thickness |
|---|---|---|
| 1.56 Standard | ±0–2.00 | Baseline |
| 1.61 Mid-Index | ±2.00–4.00 | ~20% thinner |
| 1.67 High-Index | ±4.00–6.00 | ~30% thinner |
| 1.74 Ultra | ±6.00+ | Thinnest available |
Tips
- Strong CYL (astigmatism) also benefits from higher index
- Small round frames hide lens thickness best
- Always add anti-reflective coating on high-index lenses
Coatings overview: Lenses and Coatings