Spectacle Lenses
There have been tremendous developments in lens material and design
over the last few years and there is no substitute for talking to a knowledgeable person about your prescription to make sure you know the options that are available to you. At our practice all our dispensing opticians are fully qualified and are registered with the General Optical Council and the Federation of Dispensing Opticians, having proven their capabilities to them.
The next few paragraphs tell you more about the range on offer
but the element we can offer that is often not available is knowledgeable advice from qualified dispensing opticians. We can advise you on which style will suit your facial characteristics and your prescription, this is an incredibly useful starting point. If you see a particular frame that you like but it isn’t quite right we will be able to tell you which other frames are that little bit bigger / smaller, in that different colour that you’re looking for, or just very similar but in a different price bracket. These are some of the benefits of having qualified dispensers who know their frame stock. We have the technology to take pictures of you with trial frames on and then replay them to you so you can see them on a computer screen with your own prescription on. You are now empowered to be able to choose with the benefit of knowing what your options are.
Single vision lenses:
As the name suggests they correct just one power and are the type used whenmaking up just reading or distance spectacles.
Two different powers are incorporated into the one lens, with part of the lens being dedicated to distance vision and the lower part having a definite area (the segment) given over to close work. Segments can be made with different shapes and sizes and are normally discernible when looked at closely.
Again the top of the lens is dedicated to distance vision and the lower area to close work but there is a gradual transition from one to the other. The reading area in this type of lens is not as wide as with most bifocals but they have no sudden change from one power to the other and have no distinguishing lines on them. There are areas of blurring or distortion at the edges of the reading area and it is necessary to move your head slightly when reading across wide areas. Some lenses have more marked areas of distortion and although we will not use some of the cheapest lenses where this distortion is most marked we can also offer a wide range of types of varifocals where these are minimised. We are one of the few opticians able to supply the very latest individually designed varifocals from both Rodenstock and Zeiss – they are a premium lens whose performance matches their price.
The optical density (refractive index) of a material dictates how much that material ‘bends’ light as it passes through it. The higher the refractive index the less substance of lens that is required to bend or focus the light. In olden days there was just glass (slightly higher index) or plastic to choose from but now there are high index versions of glass or plastic which can be used to help improve the cosmetics of your spectacles.
The clever solution for short sight
High index lens materials from Carl Zeiss can make your lenses thinner.
How? As their name suggests, "high index" lenses are made of materials with a high refractive index. This allows us to make lenses with higher powers thinner - and thinner also means lighter. Depending on your prescription, you can choose between 4 glass lenses and 2 plastic lenses with high index properties.
How much thinner can we make your lenses? With Lantal® 1.9, we can reduce the edge thickness of your lenses by as much as 40%
. 
See for yourself: use your mouse to move the arrow to the left. We think you'll
agree - the result is impressive!
Aspheric lenses:
When you look through the centre of a lens there is a minimum of distortion of the light but when light passes through off centre parts of the lens some distortion is experienced, the further out the greater the distortion. Aspheric lenses have more complicated surfaces ground on them to minimise this effect giving you a truer image. Another great advantage of these lenses is that they make the lenses thinner and lighter, particularly when used with high index materials.
Carl Zeiss puts your lenses on a diet
If you are farsighted, you'll certainly be aware of the problem:
Your lenses have a pronounced outward curvature and are thick; they magnify your eyes - and they are heavy.
The solution: Clarlet® 1.67 AS from Carl Zeiss.
The benefits:
High index materials and optimized lens design for maximum visual quality.
The result:
A reduction in curvature and weight by an astounding 50% - and all with optimum optical quality. With Zeiss lenses you'll not only see better, you'll actually look
better.
Reactolite is the name most people associate with this type of lens and a lot of people use the term in much the same way we call a vacuum cleaner a Hoover, it is in fact the trade name of one particular type of lens. This lens was first produced as a spin off from the space race in the 60’s but it has now evolved far past its early forms. It is a lens that changes from light to dark and back again depending on the light it is in. Although it was originally only available in glass, plastic versions have become available over the last few years. Some of the original plastic versions performed quite poorly and had some ‘interesting’ colours. Now you can have faster reacting, less temperature dependant lenses in a choice of colours including some that work just as well behind a car windscreen – ask about them, not all photochromics are the same.
As well as the variable tint available with photochromics we can offer a full range of fixed tints to both glass and plastic lenses. A polarised lens will be particularly helpful when involved with work or hobbies on or near water as it cuts out reflected glare.
Glass is a brittle material and will break easy if hit yet resists scratching well. Plastic lenses are more impact resistant but will scratch more readily and polycarbonate lenses are virtually unbreakable bur are very prone to scratching. To increase the safety of glass lenses they can be made thicker (this increases their weight) and treated with heat or chemicals to toughen them. Plastic or polycarbonate lenses are lighter but benefit from a scratch resistant coating. We are able to provide safety spectacles to meet British Standards and have a range of sport specific goggles and frames available to try.
These can be split into two main types
Hard coats:
These are applied to plastic lenses to make them scratch resistant, please note that this does not mean that they are scratch proof but they tend to stand up to minor abuse better than an untreated lens. These are particularly worth considering if you are likely to be taking your specs on and off a lot or if your lens is a more expensive type.
Vision through uncoated
Clear visibility with coated
lenses lenses
Anti reflection coating:
This is actually a series of layers and has the effect of stopping reflections off the surfaces of the lens. Normally when light hits the surface of the lens approximately 8% of the light is reflected back; with this type of coating that amount is cut to less than 1%. This gives many advantages, particularly when driving at night or working on a VDU and also improves the cosmetic appearance of the lens. It becomes more necessary on high index lenses, particularly glass versions, but otherwise should be thought of as an enhancement rather than a necessity. It is similar to having a radio in your car, it isn’t necessary but having experienced it few people would choose to be without it. It is a coating that needs to be kept clean to be effective and we do not recommend it to people who tend to finger or fidget with their lenses a lot as they would find it more annoying.
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