What does 1.61 high index mean?

Lens Index is the measurement of the thickness of an eyeglass lens. The higher the index number, the thinner and lighter the lens. A lens index is calculated by dividing the lens’ refractive index by its prescribed power. The most common lens indexes are 1.50, 1.57, 1.59, 1.60 and 1.67.

Intro

Lens index is the measurement of the thickness of a lens. The higher the lens index, the thinner and lighter the lenses. High-index lenses are made from materials that bend light more efficiently, allowing your prescription to be ground into a thinner lens.

Depending on the visual condition you need to correct, a contact lens prescription should indicate which lens index you need to achieve the best vision correction. Lens index is calculated by dividing the lens’ refractive index by its prescribed power.

A good rule of thumb is to consider high-index lenses if you require a strong vision prescription (-4.00 or above). These lenses provide the thinnest, lightest and most cosmetically appealing eyewear available today. 

When Lens Index Matters

The most common lens indexes are 1.50, 1.57, 1.59, 1.60 and 1.67, which is the thinnest and lightest of them all.

However, if your prescription is powerful, you might need a stronger lens index, such as 1.74, or else polycarbonate lenses (1.59). You may have a higher prescription if the refractive error causing vision problems is severe.

Lens index matters when choosing eyeglasses. You may want thinner and lighter or thick lenses, which can make your glasses more comfortable to wear and can improve your cosmetic appearance by reducing the so-called “bulge factor.”

Here’s a quick primer on the types of index materials, including how it affects your glasses and sunglasses.

Types of Lens Index Materials

There are different lens materials, each with advantages and drawbacks. The best lens material for you depends on your prescription and the type of frames you prefer (or select).

1.5 Standard Index

The 1.5 standard index lens is the most popular lens material and is available in many variations. They are the thickest lens, and they boast superior clarity with a single conventional vision.

Standard index lenses are for people with low SPH (spherical) correction prescriptions of +/- 2.25 and less, or a CYL (cylinder) correction of +/- 1.50 and less. They are also a way to save money on prescription lenses because they are standard lens and carry no upgrade costs.

1.56 Mid-Index

1.56 Mid-Index lenses are thinner and lighter than standard 1.5 lenses. They are about 15 percent thinner than standard 1.5 plastic lenses, and eyewear professionals recommended them for full-rim eyeglass frames and glasses for people who enjoy an active lifestyle.

1.57 Thin and Light Index

1.57 thin and light index lenses are thinner and lighter than regular lenses, making them ideal for people who need a moderately strong prescription. Most suitable to those with prescription power ranging from +/- 5.00 and +/- 4.00, and a CYL correction of +/- 3.00 and less.

1.59 Polycarbonate

Polycarbonate lenses are made from thinner, lighter and stronger materials than standard plastic lenses. They are highly flexible, allowing lenses to be made in various shapes and sizes.

The high flexibility of this lens material makes it more comfortable to wear than other lens materials for people with strong prescriptions.

1.59 Polycarbonate lenses are also more impact-resistant than regular plastic or glass lenses, making them perfect for children and people in an environment where eye injuries are possible. The lenses also provide 100 percent UV protection and superior scratch resistance.

You can choose lens coatings with them, including scratch-resistant or anti-reflective coating, to make up for any possible color differences or add further protection. 

1.61 High Index

This lens is a great mid-range option. It has a slightly higher refractive index than 1.59, but it still is much thinner and lighter than standard plastic lenses. Eyeglass professionals recommended them for people who look modern with a prescription of +/- 4.00 to +/- 6.75 and  CYL correction between +/- 2.25 to +/- 3.00.

1.67 Ultra High Index

Ultra-High index lenses are made of a dense material, which allows them to block 100 percent of UV rays and resist scratches. They are perfect for thin eyewear frames or those with a strong prescription of SPH correction of +/- 7.00 and +/- 9.00, and CYL correction of +/- 3.25 and +/- 4.00. 

The material also offers the best balance between cost and thickness. These lenses also work great in fashion eyewear.

High index 1.74

High index 1.74 lenses are today’s thinnest, flattest and most cosmetically elegant lens material. These lenses are more than 50 percent lighter than standard plastic lenses and 20 percent thinner than 1.56 polycarbonate lenses.

They are an excellent choice for rimless metal frames or semi-rimless frame styles, where the edges of the lenses are visible.

The lenses are recommended for people with high prescriptions between SPH correction of +/- 9.25 and more and a CYL correction between +/- 4.25 and +/- 6.00. The thinner lens profile will make the lenses appear smaller in your frames, making them more attractive and comfortable to wear all day long.

Who Needs High Index Lenses?

High index lenses are an option for anyone who needs to wear slimmer correctives. However, they are recommended for people with stronger prescriptions for nearsightedness, farsightedness, or astigmatism. They are also suggested for rimless frames as they are more secure and look more natural.

The table below shows the recommended lens index for each prescription.

Recommended Index Lens

Lens IndexCharacteristicsSPHCYL1.74 Index Lens -35%Thin, Comfortable Superior DurabilityHigh Impact Resistant MaterialBest for the highest prescriptions.+/- 9.25 and above4.25 to -6.00or+4.25 to +6.001.67 Index Lens-30% Thinnest, flattest and lightest lensesBest for extra-strong prescription+/- 7.00 and +/- 9.00 +/- 3.25 and +/- 4.001.6 Index Lens -25%   The thin, lightweight and a sleek designBest for a stronger prescription+/- 4.00 and +/- 6.75, +/- 3.00 and less1.59 Index Lens-20%100% UV ray protectionDurable and impact-resistant    +/- 3.00 and less1.57 Index Lens-15% Thinner and lighter than standard 1.50 lensesCustomizable  Best for moderate, strong prescription+/- 5.00 and +/- 4.00+/- 3.001.5 Index Lens-15% Traditional single-vision lenses.  Prices begin at $0.+/- 2.25+/- 1.50

What are the Differences Between 1.57 and 1.61 Lenses?

The main difference between 1.57 lenses and 1.61 lenses are the thickness of the lenses at the edges: With 1.61 index lenses, your glasses will be ultra-thin at the edges, giving them a stylish look than with 1.57 index lenses which are thin.

A 1.61 lens is recommended for the highest prescriptions, while a 1.5 lens is best for moderate, strong prescription.

How to Determine Your Lens Index?

The best way to know what lens index is right for you is by talking with one of our experienced opticians who can help you choose a pair of glasses that work best for your lifestyle and budget needs. You will first need to have a complete eye exam to receive a suitable prescription based on your exam results.

References

If you find yourself in the position to purchase a new pair of glasses, you may stumble across the phrase “lens index.” 

Lens index is a measurement on the lens thickness chart that dictates the thickness of your lenses. Made from higher-quality material, a high index lens will be able to deliver more powerful correction without the need for thicker lenses. 

What is a Lens Index?

The lens index is a numerical representation of the refractive capabilities of a lens’s material. Certain materials, especially those in high index lenses, are able to bend light more efficiently.

What is a High Index Lens?

A lens that is rated at a higher index can slow and bend light rays more effectively than standard index lenses. Because the quality of the material uses light more efficiently, the need for additional material to alter the path of light rays is unnecessary. 

Simply put, if you have high index lenses, they will be thinner. Conversely, if your prescription glasses are fitted with lower lens index material, they will be thicker.

The lens index chart ranges between 1.5 standard index to 1.74 high index.

Lens Materials

The quality of a lens is measured on the lens index chart. A difference in the lens index of your glasses can have a dramatic effect on your lifestyle. Low lens index glasses will be thicker but more affordable and only offer a low vision correction level. High index lenses have less material, making them thinner, lighter, and customized to address a wide range of vision correction.

1.5 Standard Index

A 1.5 standard index lens is suitable for people with a weak prescription looking for an affordable option. 

1.5 standard index lens are suitable for prescriptions with an:

• SPH correction of +/- 2.25 and less, or;
• CYL correction of +/- 1.50 and less

1.56 Mid-Index

The core difference between a 1.56 mid-index lens and 1.5 standard lenses is the lens’s thickness. A 1.56 mid-index lens will still require full-rim glasses but can be useful for athletes during physical activity. 

1.57 Thin & Light Index

People who require a moderately strong prescription can choose 1.57 thin & light index lenses as they are thinner and lighter than standard lenses.

1.57 thin & light index lenses are suitable for prescriptions with an:

• SPH correction of +/- 5.00 and +/- 4.00, and;
• CYL correction of +/- 3.00 and less

1.59 Polycarbonate

1.59 index lenses are incredibly resilient, offer UV protection, and are impact resistant. These lenses are made from a unique polycarbonate material and can be tailored to the individual. Coatings such as scratch-resistant or anti-reflective can be applied to 1.59 index lenses for additional security.

1.61 High Index

1.61 high-index lenses offer an ultra-thin option for those looking for a modern, stylish look. Able to be fitted into thin frames, 1.61 high-index lenses are perfect for everyday wear. 

1.61 high-index lenses are suitable for prescriptions with an:

• SPH correction of +/- 4.25 and +/- 6.75, and;
• CYL correction of +/- 2.25 and +/- 3.00

1.67 High Index

1.67 high index lenses are incredibly thin and light, even surpassing 1.61 high-index lenses. This lens index is an excellent option for those with an extra-strong prescription.

1.67 high index lenses are suitable for prescriptions with an:

• SPH correction of  +/- 7.00 and +/- 9.00, and;
• CYL correction of +/- 3.25 and +/- 4.00

1.74 High Index

The thinnest option available and designed for those with the highest prescriptions, 1.74 high index lenses are the optimal choice if you have a high prescription. 

1.74 high index lenses are suitable for prescriptions with an:

• SPH correction of  +/- 9.25 and more, and;
• CYL correction of +/- 4.25 and +/- 6.00

Do You Need High Index Lenses?

If you’re looking for a pair of glasses that are light, can be set in semi-rimless or rimless frames, and have a sleek modern look, high index lenses may be the best choice for you. However, if you’re physically active throughout the day or frequently engage in sports, a pair on the lower end of the lens index may be more suitable. 

Keep in mind, you should speak with an optician before deciding on the lens material. 

Lens Index FAQs

What are the materials used in high index lenses?

High index lenses are constructed from a specific polymer that can bend and refract light more efficiently, requiring less physical material than standard index lenses.

Why do high index lenses cost more than standard index lenses?

The material used in the manufacturing of high index lenses inherently costs more to produce. While the lenses may be more expensive than standard index lenses, the benefits far outweigh the extra cost.

Do I need high index lenses?

If you’ve been given a strong prescription to correct your vision, high index lenses are an optimal choice. These lenses are extremely lightweight, making them comfortable to wear all day.  They can be fitted to a variety of frames, allowing you to pick a pair that matches your personality.

Shop at Felix Gray

To find the best frames, Felix Gray offers the variety you want regardless of your lens index. Combined with our innovative lens technology, such as Blue Light filter glasses and sleep glasses, you’ll fall in love with your new pair of glasses. Contact Felix Gray today, and shop with peace of mind thanks to our free shipping and free returns policy.