High Index Lenses: What They Are and How to Choose the Right Index

High index lenses are prescription eyeglass lenses made from materials that bend light more efficiently than conventional lower-index plastic. That extra refractive efficiency allows the required prescription power to be produced with less curvature or material thickness under comparable conditions, which is why high index lenses are especially useful when stronger prescriptions begin to look bulky.

But choosing a lens index is not as simple as picking the highest number. A 1.74 lens has greater thinning potential than a 1.67 lens, yet the finished result also depends on prescription strength, cylinder power, frame size, lens shape, pupillary distance, how well the eyes are centered in the frame, and the optical design of the lens.

For many people, the best result comes from balancing all of these factors rather than automatically choosing the thinnest material available.

What Are High Index Lenses?

The lens index, or refractive index, describes how strongly a lens material bends light. A material with a higher refractive index can generally produce the same prescription power with less curvature and less physical thickness than a lower-index material.

Conventional plastic lenses are commonly around 1.50 refractive index. Higher-index prescription lens materials include options around 1.60, 1.67, and 1.74.

This becomes increasingly useful as prescription strength rises. Strong minus prescriptions for myopia tend to create thicker outer edges, while stronger plus prescriptions tend to create more center thickness. Choosing an appropriate higher-index material can help control that bulk.

High index does not change the prescription itself. The goal is to produce the prescribed optical power in a more compact lens form.

What Does Lens Index Mean?

A higher lens index means the material has greater refractive power. In practical terms, that gives the lens designer more ability to reduce curvature and thickness while maintaining the required prescription.

This is why the numbers printed beside lens materials matter:

• 1.50: Conventional plastic reference point
• 1.56: A step above basic conventional plastic and used by Olet as an entry-level lens option in applicable lens types
• 1.60: A common high-index option offering a useful balance of thickness control and optical performance
• 1.67: A higher-index material commonly chosen for stronger prescriptions
• 1.74: One of the highest commonly available plastic lens indexes when additional thickness reduction is important

You may also see labels such as 1.61 high index lenses in product catalogs or search results. Lens materials from different manufacturers can use slightly different index values and formulations, so 1.60 and 1.61 should not automatically be assumed to be identical materials. Olet Optical currently uses 1.60 as its standard option in this range.

How Much Thinner Are High Index Lenses?

There is no single percentage that applies to every pair of glasses.

Manufacturers commonly demonstrate meaningful thickness reductions when higher-index materials are compared with standard 1.50 plastic under similar conditions. However, the finished thickness of your actual glasses depends on much more than refractive index.

Important variables include:

• Sphere power
• Cylinder power and axis
• Lens diameter
• Frame width and height
• Pupillary distance
• How far the pupil sits from the geometric center of the lens
• Lens design
• Minimum center or edge thickness required for the material and construction

This explains why two people with similar prescriptions can receive glasses with noticeably different lens thicknesses.

It also explains why a smaller, well-centered frame with 1.67 lenses can sometimes produce a better-looking result than a very large frame fitted with 1.74 lenses.

High Index Lens Options: 1.60, 1.67 and 1.74

There is no universal prescription cutoff at which everyone should move to a particular index. The correct choice depends on the complete prescription and frame.

Lens Index	Main Advantage	When It Becomes Useful	What to Consider
1.60	Moderate thickness reduction with a balanced optical profile	When lower-index lenses begin to look bulkier than desired	Often a practical first step into high-index materials
1.67	Stronger thickness control	Moderate to strong prescriptions where lens bulk becomes more noticeable	Often provides an effective balance between thinning, optics and cost
1.74	Greater thinning potential among common plastic lens materials	Strong prescriptions where additional thickness reduction has meaningful value	Usually costs more and is not automatically the best choice for every prescription

1.60 High Index Lenses

1.60 can be an excellent option when conventional lower-index lenses are beginning to look thicker than desired but the prescription does not require maximum thinning.

It is often attractive because it offers a noticeable step up in refractive efficiency without automatically moving to the highest-index material.

When paired with a sensible frame size, 1.60 can produce a clean result for many mild-to-moderately strong prescriptions.

1.67 High Index Lenses

1.67 is one of the most widely considered high-index materials for stronger prescriptions. It provides greater thinning potential than 1.60 and can substantially reduce visible edge or center bulk when the prescription and frame make that extra index useful.

For many wearers, 1.67 provides a strong balance between thickness reduction, optical performance and price.

That does not mean every strong prescription should automatically use 1.67. Frame dimensions and the wearer's pupil position can make just as much difference to the finished result.

1.74 High Index Lenses

1.74 offers greater refractive efficiency and can provide additional thinning when lens thickness is already a significant concern.

Its benefit becomes more relevant as prescription strength and required lens diameter increase. However, the improvement from 1.67 to 1.74 may be modest in some frame and prescription combinations.

That is why 1.74 should be selected because it solves a real thickness problem, not simply because it has the highest number.

For a deeper comparison, read our 1.67 vs 1.74 High Index Lenses guide.

Do You Need High Index Lenses?

High index lenses become most useful when a prescription produces enough lens thickness that reducing bulk would meaningfully improve the finished glasses.

You may want to consider a higher index when:

• Your current lenses have noticeably thick edges or centers
• You have a stronger minus or plus prescription
• Cylinder power adds meaningful thickness to the finished lens
• You want to reduce visible lens bulk in the selected frame
• You are comparing different lens materials for a high prescription

But there is no single prescription number that determines the answer for everyone.

A prescription that works well in 1.60 in a compact frame may need 1.67 or 1.74 in a much larger frame. Conversely, changing to a smaller and better-centered frame may sometimes reduce thickness more effectively than moving up one index level.

Why Frame Size Matters So Much

Frame choice is one of the most underestimated factors in high prescription glasses.

For a minus lens, thickness increases as the lens extends farther away from the optical center. A wider or deeper frame therefore creates more lens area outside the central viewing zone, which can increase visible edge thickness.

Eye position matters for the same reason. If the pupil sits far from the geometric center of the lens opening, the lens may need more decentration, increasing the amount of material needed on one side.

A smaller frame that positions the eyes relatively close to the center of the lenses can therefore make a significant difference.

For stronger prescriptions, useful frame characteristics often include:

• Controlled lens width
• Moderate lens height
• Good pupil centering
• A secure bridge fit
• Full-rim construction when hiding edge thickness is a priority

This is one reason our High Prescription Glasses Guide treats the frame and lens as one system rather than separate buying decisions.

Does 1.74 Always Look Better Than 1.67?

No.

1.74 has greater theoretical thinning potential, but the finished difference depends on the prescription and frame. If the lens opening is already compact and the prescription is well managed in 1.67, moving to 1.74 may create only a small visible improvement.

On the other hand, a very strong prescription or a frame that requires a larger lens diameter may make the additional refractive index more useful.

The correct comparison is therefore not simply:

“Which number is higher?”

It is:

“How much practical improvement will this index produce in this prescription and this frame?”

Are High Index Lenses Always Lighter?

No. Thinner and lighter are related, but they are not the same thing.

Higher-index materials can reduce the volume of lens material needed, but different lens materials also have different densities. A thinner high-index lens is therefore not guaranteed to weigh dramatically less than a lower-index lens.

Finished glasses weight also includes the frame itself. A lightweight frame with a smaller lens opening may sometimes provide a larger comfort benefit than changing index alone.

For that reason, weight should be evaluated as part of the entire pair rather than inferred only from the lens index number.

High Index Lenses vs Regular Lenses

The main advantage of high index lenses over conventional lower-index plastic is refractive efficiency.

Both can provide the correct prescription. High index material simply gives the lab more ability to produce that prescription in a slimmer lens form.

For a mild prescription, the visible difference may be small. As prescription power becomes stronger, the thickness advantage becomes more meaningful.

This means high index is not automatically necessary for every pair of prescription glasses. The material should solve a real problem rather than simply act as an upgrade label.

High Index Lenses vs Polycarbonate

Polycarbonate and high-index lenses solve different problems.

Polycarbonate is valued particularly for impact resistance and low weight. Higher-index materials such as 1.67 and 1.74 are especially useful when maximum thickness control becomes a priority in stronger prescriptions.

For some wearers, impact resistance is the more important consideration. For others, reducing edge or center thickness matters more.

Because the intent is different, we cover this comparison separately in High Index Lenses vs Polycarbonate.

Optical Quality and High Index Lens Trade-Offs

A higher refractive index is not a quality score for vision.

Lens material changes several optical characteristics at the same time. One of those is dispersion, commonly discussed using Abbe value. Materials with lower Abbe values have greater potential for chromatic aberration, which may appear as subtle color fringing away from the optical center.

This does not mean that high-index lenses are inherently unclear. Millions of people use them successfully, and visual performance depends on the complete lens system, including prescription accuracy, lens design, optical centration, frame fit, surface quality and coatings.

It does mean that choosing the highest possible index should not be treated as automatically superior.

Do High Index Lenses Cause Distortion?

High index lenses do not automatically cause noticeable distortion simply because they are high index.

Visual discomfort can come from several factors, including prescription changes, incorrect measurements, lens design, frame position, optical centration, adaptation, and material dispersion.

Some higher-index materials can have greater chromatic dispersion than conventional lower-index plastic. A wearer who is sensitive to peripheral color fringing may therefore notice differences between lens materials, particularly when looking far away from the optical center.

Accurate measurements and an appropriate lens design are important, especially for stronger prescriptions.

If new glasses produce persistent blur, double vision, dizziness, eye strain, or other significant visual symptoms, the prescription, fitting and lenses should be checked rather than assuming the symptoms are simply a normal feature of high-index material.

Why Anti-Reflective Coating Matters

High-index materials generally have greater surface reflectance than conventional lower-index plastic. That makes a good anti-reflective treatment particularly useful.

An anti-reflective coating can reduce distracting reflections from the front and back surfaces of the lenses. This can improve transparency and make the wearer's eyes easier to see through the lenses.

Other coating functions may include:

• Scratch-resistant hard coating
• Hydrophobic treatment to help repel water
• Oleophobic treatment to help resist oils and fingerprints
• UV protection, depending on the lens material and treatment

These functions should not be confused with the impact resistance of the lens material itself. A scratch-resistant coating improves surface durability, but it does not turn a high-index material into polycarbonate or another impact-focused lens material.

Lens Design Matters as Much as Material

Refractive index tells you about the material, but it does not describe the entire optical design.

Aspheric, atoric and digital freeform lens designs can be used to optimize lens shape and optical performance in appropriate prescriptions.

For stronger prescriptions, thoughtful lens design can help manage lens curvature, peripheral optics and the finished profile. Accurate PD and other fitting measurements also become increasingly important as prescription complexity rises.

This is why a well-made 1.67 lens in the right frame can sometimes provide a better overall result than simply choosing 1.74 without considering design or fit.

Will High Index Lenses Make My Eyes Look More Natural?

Strong minus lenses can make the eyes appear smaller through the lenses, while strong plus lenses can magnify them.

High-index materials can reduce physical lens thickness and often allow flatter lens forms, which can improve the cosmetic profile of stronger prescription glasses.

However, high index does not eliminate the magnification or minification created by the prescription itself.

If eye-size appearance is a major concern, the complete system matters: prescription power, vertex distance, frame size, lens design and index all contribute to the finished result.

Choosing Frames for High Index Lenses

Frame choice should begin before the lenses are ordered, particularly when the prescription is strong.

A few practical rules can help:

• Avoid unnecessary lens size. Larger frames usually require more lens material.
• Keep the pupils reasonably centered. Excess decentration can increase thickness.
• Consider full rims for strong prescriptions. They can help conceal remaining lens edges.
• Do not assume a thin metal or rimless frame will make the lenses look thinner. These styles can expose more of the finished lens profile.
• Evaluate frame and index together. A better frame can sometimes make a bigger cosmetic difference than moving from 1.67 to 1.74.

Reddit discussions among high-prescription wearers repeatedly raise the same question: “Why are my 1.74 lenses still thick?” The common practical issue is often not the index alone but a large lens opening or poor eye centering. This is why frame dimensions should be part of the decision from the beginning.

High Index Lenses for Strong Prescriptions

High-index materials are especially valuable when a stronger prescription creates noticeable edge or center thickness.

For many strong prescriptions, a combination of a suitable frame and 1.67 or 1.74 material can provide a substantially cleaner result than conventional lower-index plastic.

But even 1.74 has physical limits.

With very strong prescriptions, it may be useful to consider other strategies in addition to refractive index, including a smaller frame, alternative optical designs, or specialty lens constructions.

For very high prescriptions, see our Lenticular Lenses Guide. Lenticular designs use a different optical structure and may be considered in selected extreme prescriptions when conventional full-aperture lenses become impractical.

Are High Index Lenses Worth It?

They can be, when the higher index solves a real problem.

If conventional lenses would be noticeably thick in the selected frame, paying for a higher index may provide meaningful cosmetic and practical value.

If the prescription is mild and the frame is already small, the visible difference may be limited. In that situation, moving to the highest available index may add cost without an equally meaningful benefit.

A useful decision is therefore based on the expected finished result rather than the index number alone.

How Much Do High Index Lenses Cost?

High-index lenses generally cost more than conventional lower-index plastic because the lens materials and manufacturing requirements differ.

The final price also depends on the index, prescription type, lens design, coatings and other selected features.

Rather than treating 1.74 as the automatic premium choice, compare whether the additional index creates enough practical thickness reduction in your actual frame to justify the added cost.

At Olet Optical, lens pricing is shown during the lens-selection process so the index and optional features can be reviewed together before the order is completed.

How Olet Optical Approaches High Index Lens Selection

Olet Optical currently offers lens index options including 1.56, 1.60, 1.67 and 1.74 across applicable prescription lens packages.

For stronger prescriptions, we do not treat lens index as an isolated upsell. The prescription and selected frame need to work together.

When reviewing a strong prescription, useful considerations include:

• Sphere and cylinder power
• Frame width and lens dimensions
• Pupillary distance
• How the eyes sit within the frame
• Lens index
• Lens design
• Coating options

For customers with stronger or more complex prescriptions, uploading the original prescription is often the safest way to avoid transcription errors and allows the lens information to be reviewed before production.

If your main concern is a strong prescription, start with our High Prescription Glasses collection and choose the frame and lens index together.

The Bottom Line

High index lenses can make a meaningful difference when prescription strength creates noticeable lens bulk.

1.60 can provide a useful step up from conventional lower-index materials. 1.67 offers stronger thickness control and is often a practical balance for higher prescriptions. 1.74 provides additional thinning potential when the prescription and frame make that extra index worthwhile.

But the highest index is not automatically the best lens.

Prescription strength, frame size, pupil position, lens shape, optical design and coatings all influence the finished result. The most effective approach is to select the frame and lens as one system rather than choosing the highest index first and trying to make the frame work afterward.

If you are choosing glasses for a stronger prescription, explore our High Prescription Glasses collection or review our High Prescription Glasses Guide before ordering.