Refractive Index

Key features

The Refractive Index measures the speed at which light travels through a material. The higher the index, the greater the lens’s ability to refract light, making it possible to produce thinner lenses with the same dioptre power.

Shared values of the Refractive Index

• 1.50 — Standard material, good transparency and comfort.
• 1.56 — A balance between reduced thickness and strength.
• 1.60 — A thinner, lighter lens, ideal for medium prescriptions.
• 1.67 — A significant reduction in thickness.
• 1.74 — Maximum thinness, recommended for high power levels.

Impact on aesthetics and comfort

The choice of Refractive Index has a direct impact on the appearance and portability of the glasses.

• Thickness — A higher index reduces the thickness of the lens.
• Weight — Materials with a high refractive index are generally lighter.
• Aesthetics — The lenses are thinner and blend in better with the frames.
• Comfort — Lighter lenses make them more comfortable to wear every day.

Relationship with other lens characteristics

The Refractive Index interacts with other technical elements that influence visual quality and the user experience.

• Optical aberrations — High-refractive-index materials may require advanced geometries in order to reduce their thickness.
• Lens geometry — Aspheric lenses improve visual performance in high-index materials.
• Anti-reflective coating — Essential for more reflective materials.

Optical solutions

The choice of Refractive Index depends on the lens power, the frame and the individual’s aesthetic and functional requirements.

• High-index lenses — Ideal for high prescriptions and slim frames.
• Aspheric lenses — They improve visual quality in highly reflective materials.
• Premium treatments — Anti-reflective and hardening agent to optimise transparency and strength.

Isolani Experience

At Isolani Optical Centres, we select the most suitable Refractive Index based on the lens prescription, the chosen frame and aesthetic requirements, ensuring an optimal balance between visual quality, comfort and design.

• Personalised eye care advice — Choosing the most suitable material.
• Behavioural Centring — Optimisation of real-world visual performance.
• Simulation Room — Aesthetic and functional assessment of the lenses.

Ongoing support

Your eyesight needs may change over time. At Isolani Optical Centres, we offer ongoing support through non-medical eye tests and updates to your personalised optical solutions.

← Back to the Optical Glossary index

The information on this page is provided for information purposes only and relates to the field of optics and commerce. It does not contain any medical, clinical or diagnostic content.