Lens index is one of the most important factors affecting lens thickness, weight, appearance, wearing comfort, and overall visual experience. For optical retailers, wholesalers, distributors, and eyewear brands, understanding the differences between various lens indexes can help provide more professional recommendations and improve customer satisfaction.

In this guide, we will explain the differences between 1.56, 1.67, and 1.74 lenses, including thickness, weight, optical performance, recommended prescription ranges, and pricing, helping you make a more informed decision.

What Is Lens Index?

Lens index, also known as the refractive index, refers to a lens material’s ability to bend light.

Simply put, the higher the number, the more efficiently the material refracts light. This means a high-index lens can achieve the same prescription correction while using less material, resulting in a thinner lens.

General Classification of Lens Indexes

Low Index (1.50 – 1.56): Thicker lenses, lower cost

Mid Index (1.60 – 1.67): Thinner lenses, moderate cost

High Index (1.70 – 1.74): Ultra-thin lenses, higher cost

Common Lens Index Options

1.56 Lenses

1.56 lenses are considered a basic mid-index lens material and remain one of the most widely used lens options on the market.

They offer a good balance between affordability and performance, making them an excellent entry-level choice for many consumers.

Advantages

• Affordable price
• Good optical performance
• Lighter than traditional CR-39 resin lenses
• Suitable for most everyday prescriptions

Disadvantages

• Thicker than 1.67 and 1.74 lenses
• Noticeably thicker edges in higher prescriptions
• Relatively heavier

Recommended Prescription Range: 0 to ±4.00D

Best For

• Budget-conscious consumers
• Low-prescription myopia or hyperopia wearers
• Everyday eyeglass users
• First-time eyewear buyers

1.67 High-Index Lenses

1.67 lenses are among the most popular high-index lenses worldwide.

For people with moderate to high prescriptions, 1.67 lenses offer an excellent balance of appearance, comfort, and value.

Advantages

• Approximately 30–40% thinner than 1.56 lenses
• Lighter weight
• More attractive appearance
• Suitable for moderate and high prescriptions

Disadvantages

• More expensive than 1.56 lenses
• Slightly lower Abbe value
• Usually requires anti-reflective coating

Recommended Prescription Range: ±4.00D to ±8.00D

Best For

• Moderate to high myopia
• Wearers of medium-to-large frame styles
• Appearance-conscious consumers
• People who wear glasses all day

1.74 Ultra High-Index Lenses

1.74 lenses are among the highest-index lens materials commonly available today and are often considered the best choice for strong prescriptions.

Advantages

• Maximum thickness reduction
• Ultra-thin appearance
• Best cosmetic results
• Helps minimize the “coke bottle” effect

Disadvantages

• Highest cost
• Lower Abbe value
• More noticeable surface reflections
• Typically paired with premium super-hydrophobic coatings

Recommended Prescription Range: ±8.00D and above

Best For

• High myopia
• High hyperopia
• Customers seeking the thinnest possible lenses
• Premium eyewear users

Why Do High-Index Lenses Need AR Coating?

Regardless of lens index, all lenses benefit from coatings. However, high-index lenses such as 1.67 and 1.74 require anti-reflective (AR) coating.

The higher the refractive index, the more light the lens naturally reflects. Without AR coating, surface reflections can reach up to 8–10% per side.

Without AR coating, 1.74 lenses may appear overly reflective, create distracting glare, and perform poorly in low-light conditions.

Recommended Coatings for Each Lens Index

How to Choose the Right Lens Index?

Choose 1.56 Lenses If:

• The prescription is below ±4.00D
• Budget is a major concern
• Optical clarity is more important than thinness
• Wear small or medium-sized frames

Choose 1.67 Lenses If:

• The prescription is between ±4.00D and ±8.00D
• Want a balance between thinness and cost
• Wear medium or large frames
• Want thinner lenses but 1.74 is beyond your budget

Choose 1.74 Lenses If:

• The prescription exceeds ±8.00D
• Cosmetic appearance is a priority
• Wear large or fashionable frames
• Budget is not the main consideration
• Previously been bothered by thick, heavy lenses

Why Are High-Index Lenses Becoming More Popular?

As consumers increasingly seek lighter, thinner, and more comfortable eyewear, high-index lenses have become one of the fastest-growing categories in the global optical industry.

Modern lens manufacturers can now produce advanced high-index lenses with excellent optical performance, durability, and coating technologies, making them a preferred choice for both consumers and eyewear professionals.

Conclusion

Choosing between 1.56, 1.67, and 1.74 lenses depends largely on your prescription, budget, cosmetic preferences, and comfort requirements.

In summary:

• 1.56 lenses are affordable and ideal for low prescriptions.
• 1.67 lenses offer the best balance of thickness, comfort, and value, making them the most popular option.
• 1.74 lenses provide the thinnest and lightest solution for very strong prescriptions.

For optical retailers, wholesalers, distributors, and eyewear brands, understanding the characteristics of different lens indexes helps deliver better visual solutions and improve customer satisfaction.

FAQ

Q1: Are 1.74 lenses always better than 1.67 lenses?

Not necessarily. For moderate prescriptions, 1.67 lenses often provide better value for money and excellent visual performance.

Q2: Are 1.74 lenses suitable for low prescriptions?

Yes, but the thickness reduction is usually minimal, making it difficult to justify the additional cost.

Q3: Can I Notice the Difference Between 1.67 and 1.74 Lenses?

For prescriptions around ±4.00D to ±5.00D, the difference is usually very small. For prescriptions of ±8.00D and above, the difference becomes much more noticeable.

Q4: Are 1.74 Lenses Easy to Break?

No. Modern high-index lenses are durable enough for normal daily use. However, they are not as impact-resistant as polycarbonate or Trivex lenses.

Q5: Which Lens Index Is Best for Progressive Lenses?

For progressive lenses, the recommended lens index depends on the prescription strength. Many wearers with presbyopia and moderate myopia prefer 1.67 high-index progressive lenses because they offer a thinner and lighter design without the higher cost of 1.74 lenses.