If you have a stronger glasses prescription, you may already know the frustration of thick, heavy lenses.
Perhaps your lenses stick out from the side of your frames. Maybe your glasses feel heavier than you would like. Or maybe you have avoided certain frame styles because you were worried your lenses would look too bulky.
The good news is that modern lens technology has come a long way.
High-index lenses are designed to make stronger prescriptions thinner, lighter, and often more comfortable to wear. They can also help your glasses look more elegant, balanced, and flattering.
But what exactly are high-index lenses? Do you need them? And are they worth the extra investment?
Let’s make it simple.
What are high-index lenses?
High-index lenses are glasses lenses made from a special material that bends light more efficiently than standard plastic lenses.
All prescription lenses work by bending light so that it focuses correctly on your retina, helping you see clearly. With a stronger prescription, a standard lens usually needs more material to achieve the correction required. That extra material can make the lens thicker and heavier.
In short, high-index lenses are often a great option for people who want their glasses to feel more comfortable and look less bulky.
What does “index” actually mean?
The “index” refers to the refractive index of the lens material. That sounds technical, but it simply means how efficiently the lens bends light.
A standard plastic lens usually has an index of around 1.5. High-index lenses have a higher number, such as 1.6, 1.67 or 1.74.
As a general rule, the higher the index, the thinner the lens can be.
So, for example, a 1.74 high-index lens will usually be thinner than a 1.6 lens for the same prescription.
High-index lens thickness chart
High-index lenses come in different levels. The higher the number, the more efficiently the lens bends light, which usually means the lens can be made thinner.
| Lens index | Often suitable for | What it means |
| 1.5 standard lenses | Lower prescriptions | A standard plastic lens option, usually fine for mild prescriptions |
| 1.6 or 1.61 high-index lenses | Moderate prescriptions | Thinner and lighter than standard lenses |
| 1.67 high-index lenses | Stronger prescriptions | A popular option for noticeably thinner lenses |
| 1.74 high-index lenses | Higher prescriptions | One of the thinnest plastic lens options commonly available |
| 1.9 high-index lenses | Very high prescriptions | An ultra-thin glass lens option, but not suitable or necessary for everyone |
This chart is only a guide. Your final lens thickness will also depend on your prescription, frame size, frame shape, and how well your eyes sit within the frame.
For example, 1.74 high-index lenses are usually thinner than 1.67 high-index lenses for the same prescription. However, a smaller, well-chosen frame with a 1.67 lens may sometimes look better than a large oversized frame with a thinner lens material.
That is why lens choice and frame choice should always be considered together.
Who are high-index lenses for?
High-index lenses are most commonly recommended for people with stronger prescriptions. They can be especially useful if you are:
- Short-sighted, also known as myopic, and your lenses are thick around the edges
- Long-sighted, also known as hyperopic, and your lenses are thicker in the centre
- Wearing varifocals or more complex lenses
- Concerned about lens thickness or weight
- Looking for a more refined appearance
- Choosing frames where lens thickness may be more noticeable
- Wearing your glasses all day and wanting better comfort
If your prescription is mild, you may not notice a huge difference from choosing high-index lenses. But if your prescription is stronger, they can make a very noticeable improvement to both comfort and appearance.
Do you need high-index lenses?
You may benefit from high-index lenses if your current glasses feel thick, heavy, or visually bulky. They are often worth considering if:
- Your lenses are noticeably thick at the edges or centre
- Your glasses feel heavy on your nose or ears
- Your eyes look smaller or larger behind your lenses
- You have avoided certain frames because of lens thickness
- You have a stronger short-sighted or long-sighted prescription
- You want thinner spectacle lenses for a more refined appearance
- You wear your glasses all day and want them to feel lighter
However, not everyone needs high-index lenses.
If your prescription is mild, the difference between standard lenses and high-index lenses may be minimal. In that case, your frame choice, lens coatings, and fitting may make more difference than choosing the thinnest lens material.
An optician can help you decide whether high-index lenses are genuinely worthwhile for your prescription, rather than simply choosing the most expensive option.
High-index lenses and frame choice
A common mistake is thinking that high-index lenses alone will solve every thickness issue.
They help enormously, but the frame still plays a big role.
If you have a strong prescription, a smaller, well-chosen frame will usually give a better result than a large oversized frame. This is because larger lenses require more lens material, which can increase thickness, even when high-index materials are used.
Good frame choices for stronger prescriptions often include:
- Smaller or medium-sized frames
- Round or oval shapes
- Full-rim frames
- Acetate frames that help disguise lens edges
- Frames where your eyes sit nicely centred within the lenses
Frames that may be less suitable include very oversized styles, very thin metal rims, rimless frames, or shapes where your eyes sit far from the centre of the lens.
With the right styling advice, you can still find frames that are exciting, flattering, and full of personality. The key is choosing eyewear that works beautifully with your prescription, rather than fighting against it.
At Clarke & Roskrow, this is exactly where our expert frame-styling advice can make all the difference.
The benefits of high-index lenses
High-index lenses can offer several important benefits, especially if you have a stronger prescription.
| 1. Thinner lenses | High-index lenses can be made thinner than standard lenses.Can reduce the bulky appearance sometimes associated with stronger prescriptions and help your glasses look more refined. |
| 2. Lighter glasses | Use less material, which can often feel lighter than standard lenses.Less likely to slip down your nose, especially when paired with a well-fitted frame. |
| 3. Flattering appearance | Thick lenses can sometimes change how your eyes look behind your glasses.Minus lenses for short-sightedness can make the eyes look smaller, while plus lenses for long-sightedness can make them look larger. High-index lenses can help reduce this effect, creating a more natural and flattering appearance. |
| 4. More frame options | Can open up more possibilities when choosing frames.Although frame choice still needs to be considered carefully, high-index lenses may allow you to enjoy a wider range of styles than you could with standard thicker lenses.This is particularly helpful if you want glasses that feel stylish, individual, and exciting rather than purely practical. |
Are there any disadvantages to high-index lenses?
High-index lenses are not automatically the best choice for everyone.
They can cost more than standard lenses because the materials and manufacturing process are more advanced. They can also be more reflective than standard lenses, which is why an anti-reflective coating is usually recommended.
Some high-index materials may also need a little more care, as they can be more delicate than certain standard lens materials.
The important thing is to choose the right lens for your individual needs, rather than simply choosing the thinnest or most expensive option available.
Common questions about how high-index lenses look and feel
High-index lenses are often chosen because they help reduce the appearance of thick lenses in glasses. But it is also useful to understand what they can and cannot do.
Do high-index lenses cause distortion?
High-index lenses do not automatically cause distortion, but lens design, frame choice, prescription strength, and measurements all affect how your vision feels.
With stronger prescriptions, some edge distortion can be more noticeable, especially in larger frames. Choosing the right frame shape and taking accurate measurements can help your lenses perform more comfortably.
Do high-index lenses reduce distortion?
High-index lenses can help reduce the cosmetic effects of thicker lenses, but they are not the only factor in reducing distortion. The frame size, lens design, fitting position, and your prescription all matter.
Do high-index lenses make your eyes look bigger or smaller?
High-index lenses can help reduce the magnifying or minifying effect caused by stronger prescriptions. If you are long-sighted, thicker plus lenses can sometimes make your eyes look larger. If you are short-sighted, thicker minus lenses can make your eyes look smaller. High-index lenses can help reduce this effect, creating a more natural appearance.
Are high-index lenses glass or plastic?
Most modern high-index lenses are made from advanced plastic materials. Some very high-index lenses, such as 1.9 lenses, may be made from glass, but these are not suitable or necessary for everyone. Plastic high-index lenses are generally lighter and more commonly used for everyday glasses.
Are high-index lenses polycarbonate?
Polycarbonate lenses and high-index lenses are not quite the same thing. Polycarbonate is a strong, impact-resistant lens material often used for children’s glasses, sports eyewear, or safety glasses. It is thinner than standard plastic, but it is not usually the thinnest option for very strong prescriptions.
Do high-index lenses have UV protection?
Many modern high-index lenses include UV protection, but this can depend on the specific lens material and coating chosen. Your optician can explain which lens options offer UV protection and whether any additional coatings would be helpful for your lifestyle.
Do high-index lenses need special coatings?
In many cases, yes, we would recommend considering high-quality lens coatings.
Because high-index lenses can reflect more light, an anti-reflective coating is especially useful. This helps reduce reflections on the lens surface, making your vision feel clearer and your lenses look more transparent.
Other useful coatings may include:
- Scratch-resistant coating
- UV protection
- Anti-reflective coating
- Lens treatments for driving or screen use
- Photochromic lenses that darken in sunlight
The right combination will depend on how you use your glasses every day.
For example, someone who drives at night, works on screens, and wears their glasses from morning to evening may benefit from different lens features than someone who only wears glasses for reading. That is why your lifestyle matters just as much as your prescription.
Why expert advice matters
High-index lenses are a brilliant example of why glasses should not be chosen by prescription alone. Your final result depends on several things working together:
- Prescription
- Frame size
- Frame shape
- Lens material
- Lens coatings
- Measurements
- Fitting
- Lifestyle
- Personal style
When all of these details are considered properly, your glasses can feel completely different.
At Clarke & Roskrow, we take the time to help you understand your options and choose eyewear that works beautifully for you. We will guide you through your lens choices, explain what will make the biggest difference, and help you choose frames that complement both your prescription and your personality.
Book your FREE Eyewear Styling Consultation and take the next step towards glasses that help you See Better, Look Better and Feel Better.
FAQs
Are high-index lenses worth it?
High-index lenses can be worth it if you have a stronger prescription and want thinner, lighter, more attractive glasses. If your prescription is mild, you may not notice enough difference to justify the extra cost.
What are the thinnest spectacle lenses?
For most people, 1.74 high-index plastic lenses are among the thinnest commonly used spectacle lenses. 1.9 high-index glass lenses may be thinner in some cases, but they are heavier, more specialist, and not suitable for everyone.
Can high-index lenses be tinted?
In many cases, yes, high-index lenses can be made with tint options, although availability depends on the specific lens design and prescription. Your optician can advise on the best option if you want prescription sunglasses or tinted lenses.
What is the difference between 1.67 and 1.74 high-index lenses?
Both 1.67 and 1.74 lenses are high-index lenses, but 1.74 lenses are usually thinner than 1.67 lenses for the same prescription. However, the best choice depends on your prescription, frame choice, comfort needs, and budget.
How much do high-index lenses cost?
The cost of high-index lenses varies depending on your prescription, lens index, coatings, and frame choice. At Clarke & Roskrow, we would talk you through the options and help you choose the lens that gives you the best result for your needs.
Book your FREE Eyewear Styling Consultation and take the next step towards glasses that help you See Better, Look Better and Feel Better.
