Lens Options

When browsing through the frames you will note that a variety of lens options are available, answers to some of your questions may be found below, if you need any further advice, please do not hesiste to contact us.

At a Glance

		Thickness		Powers[2]
Type	Index	Relative[1]	2.00	4.00	6.00	UV	Unbreakable
Standard	1.5	100%	3.5mm	4.0mm	6.0mm
1.6 HMAR	1.6	78%	3.2mm	3.5mm	4.7mm
1.67 HMAR	1.67	70%	3.0mm	3.2mm	4.3mm
1.74HMAR	1.74	65%	2.9mm	3.0mm	3.9mm
Transition	1.5	100%	3.5mm	4.0mm	6.0mm
Polycarbonate	1.59	80%	3.2mm	3.5mm	4.8mm

[1] Lens thickness when compared to standard index.
[2] Estimated centre thickness of a plus power lens or edge thickness of a minus power lens in specs of a standard size with an average pupil distance.

Broadly speaking...
For prescriptions where the SPH value is less than +/-3.00 there isn't a lot to be gained from having a higher index lens.
High powered prescriptions benefit from high index lenses, the higher the powers the more benefit seen.
If in any doubt contact us, we will advise you on the best option.

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Standard

The vast majority of spectacles sold in Britain make use of a light weight plastic lens material known as CR39.
Unless you are otherwise aware then this is most likely the type of lens you have in your specs, it is designed for optical use and offers excellent image quality and a good compromise between impact resistance and scratch resistance. Our standard lenses are available with a Hard anti Reflection coating (see below).

High Index lenses

High Index lenses are plastic with added ingredients to make them better at bending light (or refracting), hence the term refractive index.
The higher the refractive index, the thinner a lens will be for a given prescription.

Thin 1.6 index are approximately 20-25% thinner than standard yet are stronger than standard so are a better option for rimless frames, though for rimless we recommend Polycarbonate (see below).

Superthin 1.67 index lenses offer a thickness saving of approximately 30% over standard index.

Ultrathin 1.74 index, the thinnest plastic lenses on the market, 35-40% thinner than standard lenses.

Our high index lens options are supplied with a Hard Anti Reflection coating as standard.

Polycarbonate 1.59 Index

Polycarbonate are our preferred choice of lens for our rimless frames as it is a virtually unbreakable lens material.
It is also extremely light weight and with an index of 1.59 it offers much of the benefits of a high index lens.
We supply our Polycarbonate with an anti scratch coating as standard as the qualities which make a lens less brittle also render it less hard and therefore more prone to scratching. Polycarbonate lenses are also available with a Hard Anti Relection coating (see below).

Transitions (R)

Transitions are the market leading Photochromic lens and are available in Brown and Grey.
They have a lighter residual hue when unactivated, generally less than 10% and barely noticable.
Transitions react faster than most other brands of photochromic although we feel it sensible to point out that if you have seen the adverts on TV look out for the small print in the corner of the screen stating that the reaction has been sped up for the sake of demonstration!

Hard Anti Reflection coating

Your lenses will benefit from the added protection of the Scratch Resistant properties of this coating. No plastic lens is scratch proof however so care must be taken when handling and cleaning lenses.
From an Anti Reflection point of view there are various benefits.
Spectacle lenses reflect up to around 8% of the light reaching them on their surface but with an Anti Reflection coating this is often reduced to under 1%. The results are better cosmetics as your lenses appear clearer to onlookers and more comfortable vision as there are fewer distracting reflections on the lenses and more light passing through the lenses in low light conditions.

Ultra Violet

Prolonged exposure to Ultra Violet Radiation can cause damage to the eye.
All of our High Index, Photochromic and Polycarbonate lenses offer excellent protection against UV, blocking in the order of 99% of harmful Ultra Violet Radiation up to 400nm.

Cleaning your lenses

Your new specs will reach you in a hard case complete with a microfibre cleaning cloth.
Keeping your lenses in tip top condition is simple.

Do
• Keep your specs in their case when not in use.
• Only clean your specs with the cloth provided or a similar clean cloth intended for this purpose.
• Clean your specs once a week in soapy water and dry with a tissue.

The biggest culprits when it comes to spectacle damage are car dashboards and handbags, follow the simple rules above and your new purchase will serve you well for years to come.