If you have a high prescription, choosing the right lens index can make a noticeable difference to the appearance and comfort of your glasses. Standard lenses may work perfectly well for lower prescriptions, but lens thickness becomes a bigger concern for people with stronger prescriptions. The edges can look quite thick, the lenses may add extra weight, and the finished glasses might not look as good as expected. That’s why high-index lenses are often recommended for people with high prescriptions.

But should you choose 1.60, 1.67, 1.70, or 1.74? Is a higher refractive index always better? Not necessarily. Your prescription, frame size, lens design, and budget all play a part in making the right choice.

What Does Lens Index Mean?

Lens index, also known as refractive index, describes how efficiently a lens material bends light. A higher refractive index allows the material to bend light more efficiently, which generally means the lens can be made thinner for the same prescription.

Common lens indices available in the optical market include:

• 1.56: One of the most common choices, suitable for low to moderate prescriptions.
• 1.60: Thinner than standard 1.56 lenses, suitable for moderate prescriptions.
• 1.67: A popular high-index option for stronger prescriptions.
• 1.70: An option between 1.67 and 1.74, suitable for customers who want thinner lenses without paying as much as they would for 1.74.
• 1.74: An ultra-high-index option, often considered for very strong prescriptions.
• 1.59 PC: Polycarbonate lenses, known for their good impact resistance, although they are not classified as high-index lenses.

One thing worth remembering: a higher index does not automatically mean better optical performance or greater wearing comfort. Its main advantage is reducing lens thickness, while other factors also need to be considered.

Which Lens Index Is Best for High Prescriptions?

There is no single prescription range that works for everyone. However, the following options can help you narrow down your choices.

1.60 Index: A Good Choice for Moderate Prescriptions

For many people with moderate prescriptions, 1.60 lenses offer a good balance between thickness, weight, and price. Compared with standard 1.56 lenses, 1.60 lenses are thinner. They are suitable for people who are starting to pay more attention to lens thickness, particularly around the edges or center. For example, if your myopia is around -3.00D to -6.00D, 1.60 lenses may be worth considering. If you want a noticeable improvement in thickness but do not want to spend more on higher-index materials, 1.60 is often a practical option.

1.67 Index: A Popular Choice for High Prescriptions

If your myopia is around -5.00D to -8.00D, 1.67 high-index lenses are often a good choice. For people with high myopia, minus lenses can become quite thick around the edges. Choosing a 1.67 lens can help reduce edge thickness and give the finished glasses a neater appearance. This is particularly useful for customers who care about how their glasses look and would prefer not to have visibly thick lens edges. For many people with stronger prescriptions, 1.67 offers a reasonable balance between thinning performance and cost.

1.70 Index: An Option Between 1.67 and 1.74

Not every customer needs to move directly from 1.67 to 1.74. If they want another option between the two, 1.70 high-index lenses are worth considering. With a higher refractive index than 1.67, 1.70 lenses can provide additional thickness reduction. At the same time, they offer an alternative for customers who want thinner lenses but do not necessarily need 1.74 lenses. For some prescriptions, the thickness difference between 1.67 and 1.70 may be relatively small. The actual difference between 1.70 and 1.74 also depends on frame size and lens design. One advantage of 1.70 lenses is their more affordable price compared with 1.74. This makes them an attractive option for people with very high prescriptions who want thinner lenses but have a limited budget.

For optical shops and lens distributors, adding 1.70 lenses to the product range provides another choice between standard high-index and ultra-high-index options. Customers have more flexibility when balancing lens thickness and price.

1.74 Index: For Very High Prescriptions

If your prescription is particularly strong, 1.74 lenses may be worth considering. They are among the highest-index materials commonly used for prescription glasses and can further reduce lens thickness, making them especially useful for people with high myopia. For prescriptions above approximately -8.00D, 1.74 lenses are often considered.

However, if the frame is relatively small and well matched to the wearer’s pupillary distance, the thickness difference between 1.67 and 1.74 may not be as noticeable as expected. With a larger frame, the additional thinning effect of 1.74 may be more significant. So don’t choose 1.74 simply because it has the highest refractive index. It’s better to consider whether the improvement in thickness justifies the additional cost.

Is Lens Index Selection Different for Myopia and Hyperopia?

Yes. This is an important detail that is sometimes overlooked when choosing lenses for stronger prescriptions.

For myopia (minus prescriptions), lenses are generally thinner in the center and thicker around the edges. A higher refractive index can help reduce edge thickness.

For hyperopia (plus prescriptions), lenses are generally thicker in the center and thinner around the edges. High-index materials can also help reduce center thickness, but the actual result depends on the prescription and lens design.

This means that two people with similar prescription strengths may not necessarily need the same lens index. Astigmatism also matters. If the prescription includes a high cylinder value, lens thickness may vary across different directions. That’s why the spherical power alone is not enough to determine the right index.

What Other Factors Affect Lens Thickness?

Refractive index is important, but it is not the only factor. In some cases, changing the frame can make a bigger difference to the final appearance than moving up one index level.

1. Frame Size

Larger frames generally require larger lens diameters. For people with high myopia, this can result in thicker lens edges. Choosing a smaller frame can help reduce overall lens thickness.

2. Frame Shape

Round or oval frames can help distribute lens thickness more evenly. Wider rectangular frames may make thick edges more noticeable, especially with strong minus prescriptions.

3. Pupillary Distance and Fitting Position

The position of the wearer’s pupils in relation to the optical centers affects how the lenses are cut and fitted. Accurate pupillary distance and fitting measurements help avoid unnecessary decentration, which can otherwise increase lens thickness.

4. Lens Design

Aspheric lens designs can help improve the appearance of lenses, particularly for stronger prescriptions. Depending on the prescription and design, they may also reduce the magnified or minified appearance of the eyes.

Is 1.74 Always Better Than 1.67?

No. This is one of the most common misunderstandings when choosing high-index lenses.

Under comparable conditions, 1.74 lenses are generally thinner than 1.67 lenses. However, the improvement is not always dramatic. For some prescriptions and frame combinations, the difference may be relatively small. Price is another factor. 1.74 lenses usually cost more than 1.67 lenses, so customers need to decide whether the additional reduction in thickness is worth the extra expense. For many prescriptions between -5.00D and -8.00D, 1.67 lenses may already provide a satisfactory result in terms of appearance and wearing comfort. For stronger prescriptions, 1.74 may be a more attractive option.

The right choice is ultimately about finding a suitable balance between appearance, comfort, optical quality, and price.

FAQs

Q: Are high-index lenses worth buying?

A: For people with moderate to high prescriptions, high-index lenses can make glasses look thinner and more attractive. Whether they are worth the extra cost depends on the prescription, frame choice, and personal preferences.

Q: What is the thinnest lens index available?

A: Among commonly used spectacle lens materials, 1.74 is one of the highest refractive index options. It is often considered by people with very strong prescriptions who want to reduce lens thickness as much as possible.

Q: Can I use 1.67 lenses for -10.00D myopia?

A: Yes. Some people with -10.00D myopia can still use 1.67 lenses. However, 1.74 may offer further thickness reduction. The final choice should be based on frame size, shape, and lens design.

Q: Do high-index lenses make glasses lighter?

A: Not necessarily. High-index materials can reduce lens volume, but material density also affects weight. The final weight depends on the lens material, prescription, and frame.

Q: Should people with high myopia choose smaller frames?

A: In many cases, yes. Smaller frames can help reduce lens thickness, particularly around the edges of minus lenses. This is one of the simplest ways to improve the appearance of glasses for people with high myopia.

Which Lens Index for High Prescriptions?

For optical shops and lens distributors, keeping 1.60, 1.67, 1.70, and 1.74 lenses in the product range is a practical approach. These options cover different prescription requirements and price levels, giving customers more choices.

Aogang Optical supplies a range of high-index optical lenses, including 1.60, 1.67, 1.70, and 1.74, to wholesale customers worldwide. If you are looking for a reliable high-index lens supplier for your optical business, contact our team to learn more about available specifications and product options.