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Useful Lens Guide

prescription optical lens guide and how to reglaze glasses frames

What Lenses should you choose ?

1.5 index standard single vision lenses: 
These lenses often come free with glasses or at a small charge. The lens thickness is standard so might show a thick centre for + prescriptions or thick outer edges for minus prescriptions. The lens thickness is not generally a problem or particularly noticeable unless the powers of the prescription needed is higher than average (above 2 dioptres on Sph's) If the frame picked is particularly large on the eye size (which can lead to thicker centres or edges) then it might be worth considering the next lens up. This is called a 1.6 index lens and is approx 24% thinner than a 1.5 index lens.

1.6 index single vision lenses - thin lenses:
As stated above, these lenses are best used with a slightly stronger prescription. They offer a flatter more cosmetically pleasing thinner alternative to the 1.5 index standard lens. They are approx 24% thinner than standard lenses. These lenses offer an additional bonus, they usually come already anti glare coated. This makes the lenses less noticeable in the frame as they don't mirror light or flash back at the person viewing you, and give you an anti glare advantage, especially when driving at night and using your phone, pc etc.

1.67 single vision - ultra thin lenses:
Approx 34% thinner than standard lenses and much flatter. Cosmetically superior to 1.5 or 1.6 index lenses. These lenses are used for stronger prescriptions or wearers who want light weight lenses. These lenses also generally come with an anti glare coating but are not available with react to light photochromic lenses. If you want very light weight, flat, cosmetically pleasing glasses and have a prescription over 3 to 3.5 dioptres you should consider these lenses.

1.56 index single vision Photochromic (plastic) sun reactive lenses:
These lenses are slightly thinner than standard single vision lenses. They come with a sun reactive coating and a hardened coating. These lenses react to UV light and get darker quickly when the UV is high outside for example. These lenses return to their original virtually clear state when no UV is present like indoors.
The lenses available are in Brown or Grey. 
Points to note. Very little reaction takes place in a car behind the windscreen. This is because UV cannot generally penetrate a modern car windscreen.
These lenses don't react as quickly in low temperatures.
There is a lifespan where the lenses are at peak performance. The Lifespan is according to the manufacturer around 2 to 3 years, at which point the colour stays more apparent in the lenses, although they will still react. Photochromic lenses are not compatible with ultra thin 1.67 lenses or above.

1.5 index single vision Tinted lenses:
These lenses are standard thickness lenses with a permanent tint absorbed into the lens through to the centre. This tint process ensures that the tint colour won't wear off. The colour is permanent and won't change if exposed to uv. These lenses are ideal for sunglasses or just with a cosmetic pale tint for effect.

1.5 index Standard thickness Varifocal lenses:
Entry level varifocals with some side distortion and an average reading area. These lenses are a standard thickness and great for versatile glasses allowing vision at all distances for a low price.

1.5 index Wide Varifocals - wide band of vision for all distances: 
A superior option to Standard varifocals for a little more money (our view probably worth the extra)
These lenses are a standard thickness but can be pre-calibrated (made flatter and a little thinner) at no extra cost.
The width of vision is wider than Standard Varifocals. Less outer edge distortion is noticeable and the reading area is also wider for ease of use.

1.6 index Thinner standard varifocals Varifocals:
Cosmetically thinner for stronger prescriptions above 2 dioptres. These lenses are flatter and thinner than 1.5 index lenses. The material used is stronger and flatter. We automatically pre-calibrate these lenses too. They will be thinner and lighter to wear than standard thickness varifocals and come with an anti glare coating in the price. The option to add 1.6 thinner varifocals lenses is available throughout the ordering process online no matter what type of varifocals you choose.

1.67 index Ultra Thin standard Varifocals:
Even thinner and lighter lenses ideal for prescriptions over 4 dioptres. These lenses are exceptionally light weight, flat and thinner than our other lens options. Suitable for stronger to high prescriptions. Superb quality varifocals at a great price. The 1.67 lens option is available on any type of varifocal you choose with us online and comes with an anti glare coating in the price but not react to light photochromic lenses.

1.6 index Thin Wide band Varifocals and 1.67 Ultra Thin Wide band Varifocals:
These thinning options are also available with our higher quality wide band varifocals with an anti glare coating in the price. This combines superb wide band vision throughout the lenses as well as flatter and light weight options.

About Prisms
Some prescriptions require a prism to be added to the lens. A prism can be measured as Prism in/out/up or down or a combination of. A prism is infact simply a movement of the lenses as indicated that allows clearer sharper vision.. It often means the lenses have to be made bigger on manufacture to allow for the movement of the lens ensuring the lens centre is still neatly over your pupil when cut to fit into your spectacle frames. This requires lenses specially made for each particular frame and so costs more than a standard single vision lens. We keep our single vision lens prices low so buy them already made in bulk. There is no prism in them and it can't be added afterwards. We don't supply glasses with prisms online but do so instore.


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