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lenses on  a blu backgroundLens materials

When you’re buying a new pair spectacles, there are a number of choices you have to make. Some of them are fun: what the frames will look like, what colour they’ll be, and so on. Some choices, however, require a little more understanding of what you’re getting yourself into. Specifically: what do you want your lenses made out of?

There are five standard lens materials: polycarbonateCR-39 (‘normal’ plastic), mid-index plastic (1.56), high-index plastic (1.6 and upwards), and glass.

At Space Healthcare, you’ve got another unique choice – ultra-high index Tokai lenses

Make an appointment for an eye test, and find out more!

Glass Lenses

Glass used to be the norm in eyewear lens materials—hence the term ‘glasses’. However, compared to polycarbonate and plastic, glass has a greater chance of breaking, making it potentially unsafe.

It’s also more expensive than newer materials.

At Space Healthcare we feel we’ve got better, and safer, choices for lens materials. Consequently we don’t use glass lenses.

Polycarbonate Lenses

Polycarbonates are durable— the material is used for bulletproof vests and space shuttle windows. Polycarbonate is the best lens choice in environments like construction, sports, or warehouses, where your glasses run a risk of being broken.  The material has built-in UV protection and can stop 99.9% of harmful rays from the sun, fluorescent lights, and computer screens.

Polycarbonate lenses, however, are prone to scratching, much more so than CR-39. They are also a little more difficult to clean. Because of this, almost all manufacturers of polycarbonate automatically give it a scratch-resistant coating. Polycarbonate is the second-most widely-used lens material.


CR-39 ('normal' plastic) Lenses

CR-39 is the most widely-used lens material. If you’re looking for a specific colour tint to your prescription lenses, plastic is the best choice. It’s also more solvent-resistant and scratch-resistant than polycarbonate, which means that you can clean the lenses more easily.

On the other hand, CR-39  weighs more than polycarbonate, and will feel slightly bulkier on your face.

High-Index Plastic Lenses

MID-INDEX (1.56) and HIGH-INDEX PLASTIC (1.6, 1.67, 1.7) were developed to reduce the thickness of plastic lenses. These lenses can still be tinted, but are less bulky than CR-39. The higher the index number, the thinner the lenses.

Lens cost also usually increases with the index.

High-index lenses have, in the past, the added problem of not being suitable for people with high prescriptions, as an ultra-thin lens may not be strong enough, particularly in rimless frames. Still, it’s often far more stylish and attractive to have super-thin glasses.

The Thinnest Lenses in the World!

At Space Healthcare we’ve teamed up with Tokai Lenswear, and can offer you ultra-high index lenses with a refractive index of 1.76 – the highest index plastic lens in the world.

These unique lenses, with their extraordinarily high refractive index, will give you the thinnest and lightest glasses you’ve ever had!

Combine these lenses with our superb frames for a truly unique pair of glasses.

Laser eye surgery vision correction Leamington Spa | Optometry | Dentistry | Space Healthcare