Lens Index Guide

Lens Index measures how efficiently light bends through the prescription lens. The higher a lens' index is, the thinner it becomes.

Quick Reference Chart

Index	SPH Range	Thickness	Weight	Price
1.56	0~±2.00	Thickest	Heaviest	$
1.61	0~±4.00	Moderate	Moderate	$$
1.67	±2.00~±6.00	Thin	Light	$$$
1.74	±4.00+	Thinnest	Lightest	$$$$

1.56 Index (Standard)

• Best for: Low prescriptions | SPH Range: 0~±2.00.
• Pros: Affordable, widely available.
• Cons: Thicker edges for stronger prescriptions; not recommended for sports sunglasses. It's the heaviest, not recommended for those who require comfort.

1.61 Index (Mid-Range)

• Best for: Mild to moderate prescriptions | SPH Range: 0~±4.00.
• Pros: Around 20-30% thinner than 1.56, good clarity. It's slightly lighter.
• Cons: Slightly more expensive.

1.67 Index (Thin & Light)

• Best for: Moderate to high prescriptions | SPH Range: ±2.00~±6.00.
• Pros: Around 40% thinner than 1.56, lightweight.
• Cons: Higher cost.

1.74 Index (Thinner)

• Best for: High prescriptions | SPH Range: ±4.00 and above.
• Pros: Thinnest option (around 50% thinner than 1.56). In terms of weight, it is the lightest and most comfortable.
• Cons: Most expensive.

 

Additional Tips

• Frame Size Matters: Larger frames make lenses appear thicker - opt for higher index(1.67/1.74) if needed.
• Ask Your Optician: For astigmatism (CYL) or bifocals, they may recommend adjustments.