What are High Index 1.74 Lenses?

If you have a very strong prescription, you should consider ultra thin high index 1.74 lenses.

High Index 1.74 lenses are the thinnest, flattest, and most cosmetically appealing lens ever developed.

These ultra thin lenses are nearly 50% thinner than plastic and 5% thinner than 1.67 high index lenses, offering you the ultimate in technology and cosmetics. The thinner lens is much more flattering, reducing the distortion that high prescriptions cause when made with lower quality lenses.

Hi-index 1.74 lenses are perfect for:

• People with +/- 2, and stronger prescriptions
• People who are self conscious about the thickness of their lenses
• People who wear contacts because traditional lenses distort their eyes

What is the technology behind the 1.74 high index lens?

High index lenses have a flatter curve than their lower-index counterparts for a reduced lens profile. A flatter curve, however, can cause off-axis blurred vision. To compensate, the 1.74 lens incorporates optical aspheric technology into the lens design. Not all aspherics are created equal. FramesDirect.com provides lenses manufactured by The Essilor Group, known in the industry for having the most advanced optical performance and flattest design for aesthetic appeal.

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Also see: Understanding Your Prescription | UV Protective Coating for Lenses | Lens Materials | Transitions Lenses | I have a strong prescription. What lenses do I need?

What are High Index Lenses?

High index lenses are made from a different grade of plastic (know as the index). This allows lenses to be made thinner than ordinary standard plastic materials of a lower index.

Types Of High Index lenses:

There are three main high index lenses called:

• 1.60 High Index Lens 

• 1.67 High Index Lens 

• 1.74 High Index Lens

   

High index lenses are made of a plastic material which bends light more than standard CR39 lenses. It can therefore be made thinner and lighter, allowing for more cosmetically appealing and comfortable to wear glasses.

It's worth noting that the numbers are simply the names of the plastic and does not refer to the thickness of the lens as is often mistakenly assumed.

Standard lenses:

Standard or 'regular' lenses are made from a plastic known as CR39 and have a 1.5 index. This is the type in which all inclusive frames are made with.

(This image shows the difference in thickness of a standard 1.5 index lens & a 1.74 index lens - typically 50% thinner)

How Much Do High Index Lenses Cost?

High index lens prices:

• Option 1: Thin = 

  1.60 High Index Lens Price - £35.00

• Option 2: Ultra Thin = 

  1.67 High Index Lens Price - £55.00

• Option 3: Ultra, Ultra Thin = 

  1.74 High Index Lens Price - £135.00

Generally speaking, the higher the index, the higher the cost of the lenses; however, the more you pay does mean your lenses will be thinner and lighter.

As with most purchases in life, you get what you pay for and not all lenses are the same.

We offer many types of branded high index lenses from Essilor and Hoya to Zeiss and Kodak. All these brands are leaders in the optical industry and well-known for producing high-quality high index lenses and lens coatings.

Quite simply, you will not find better quality lenses.

We also include a free triple 'Anti Reflection, UV400 and Anti Scratch' Lens Coating worth £25.00 as standard making these lenses outstanding value:

And for peace for mind, we offer our double no risk guarantees on all purchases:

“No Quibble 30 Day, 100% Money Back Guarantee” and "Two-Year Frame & Lens Warranty".

High Index Lenses Thickness Comparison:

• 1.60 High Index Lenses are on average 20% thinner than ordinary CR39 plastic.

• 1.67 High Index Lenses are on average 35% thinner than ordinary CR39 plastic.

• 1.74 High Index Lenses are on average 50% thinner than ordinary CR39 plastic.

This example shows the difference in thickness for high index lenses.

Different High Index Lens Options:

High Index lenses are available in nearly all lens types, materials, coatings and designs, such as varifocal lenses, photochromic lenses and polarised lenses. 

High Index Lens Benefits:

High Index Lenses Are Thinner:

High index lenses are much thinner due to their ability to bend light.

As they bend light more than an ordinary lens they can be made much thinner but offer the same prescription power.

High Index Lenses Are Lighter:

As they can be made thinner, they contain less lens material and are therefore much lighter than ordinary lenses.

These benefits will increase the higher the index lens option selected.

The more the lens bends light, the thinner and lighter it will be.

Our High Index Lenses Include Free Coatings:

With fewer reflections, more light passes through the lens to the eye for good vision and the lenses look more transparent and attractive.

Anti reflection coating is especially beneficial when used on high-index lenses, which reflect more light than regular plastic lenses. 

Anti-reflective coatings allow 99.5 per cent of available light to pass through the lenses and enter the eye for good vision.

By eliminating reflections, A/R coating also makes your eyeglass lenses look nearly invisible so people can see your eyes and facial expressions more clearly. Anti-reflective glasses also are more attractive, so you can look your best in all lighting conditions.

The visual benefits of lenses with anti-reflective coating include sharper vision with less glare when driving at night and greater comfort during prolonged computer use (compared with wearing eyeglass lenses without AR coating).

How to buy high index lenses:

Buying high index lenses online is as simple as adding it to your lens options when choosing your lenses and is the quick, efficient and cheaper alternative to the high st 

Please don't hesitate to contact us should you require any further information and one of our advisers will be happy to assist you in selecting the correct high index lens option for your prescription, lifestyle and budget.

Freephone:0800 690 6220

sales@onlineopticiansuk.com

Understanding Index of Refraction:

The index of refraction is the speed of light in a vacuum divided by the speed of light in a material.

The refractive index is the extent to which light is refracted when it enters a medium. The greater the index the more refraction occurs. Air has an index of 1.0, water is 1.3 and many type of glass are around 1.5.

Higher index lenses bend light at a steeper angle than lesser index versions. 

The ‘index’ is the result given as a number: 1.5,1.6,1.67 or 1.74 and the higher the number, the more light is bent or 'slowed down'. Therefore, these lenses have less curvature for the same focal power requiring less lens substance/material.

The result being high index lenses are thinner than lesser versions but achieve the same focal power.

Further Information -

https://www.zeiss.co.uk/vision-care/better-vision/lifestyle-fashion/fashionably-sleek-highindex-lenses.html
https://www.nikon-lenswear.com.sg/products/details/nikon-lite-das
https://www.essilor.co.za/products/high-index-lenses
https://www.hoyavision.com/uk/discover-products/eye-care-professionals/lens-materials/ultra-high-index/