Spectacles at Andrew Keirl Opticians
Andrew Keirl Opticians in Liskeard are pleased to be a Hoya Specialist Optician. However, we can obtain spectacle lenses from all the major lens suppliers including Zeiss, Essilor, Rodenstock and Norville. As well as giving you clear vision, the design and materials used in modern lenses make a big contribution to the flattering appearance of today’s spectacles. Highly advanced plastics materials mean that lenses can be made thinner and lighter than ever before, even for higher prescriptions. Most lenses will benefit from a reflection-free coating which will virtually eliminate distracting reflections on both sides of the lens. These are perfect for night driving or when using a computer. Best of all, when people look at you, they will see your eyes and not a reflection from the lens.
All our lenses are premium products offering the highest standards in definition, contrast and colour. For patients with high prescriptions where lenses have been traditionally quite thick, the constant improvement in technology means we can offer increasingly lightweight and thin alternatives to the beer bottle bottom glasses of the past.
Single vision lenses are lenses that are designed for one purpose for example, to see in the distance or for reading. The prescription is stable across the surface of the lens. They are available in most prescriptions and also for patients who require very strong or complex lenses. Single vision lenses offer a wide variety of available materials so that wearers will benefit from thinner and lighter lenses. Advanced lens designs known as aspheric lenses not only enhance the cosmetic appearance of the lens but also provide optimum vision from the centre to the edge of the lens. Andrew Keirl Opticians recommend “clever” reading lenses known as enhanced reading lenses that give clear vision from the usual 40 cms to arms length distances. These are ideal for use with a laptop or tablet computer and also for a host of other hobbies and interests such as cooking, board games, music etc.
A bifocal lens provides two prescriptions and was the original method of providing distance and close-up in the one lens. It is said that the bifocal was invented by Benjamin Franklin who was fed up with constantly changing his spectacles. Although the types of bifocals lenses available have become limited in recent years, bifocals are still available and are preferred over varifocals by some patients. Bifocal lenses have a noticeable dividing line between the distance and near portions and do not give mid-distance vision. In order to overcome the lack of mid-distance vision with bifocal lens, a trifocal lens is occasionally recommended.
Thin, light and safer lenses
Given the choice, most patients would not choose to wear a thick or heavy spectacle lens! At Andrew Keirl Opticians in Liskeard we will spend time with you during the dispensing of your spectacles to ensure that you receive the right product for your prescription. Most spectacle lenses these days are usually manufactured from a plastics or resin material of one sort or another. Glass lenses are rarely dispensed as they tend to be heavy and are prone to breaking. However, in certain circumstances and for very high prescriptions, a glass lens may be the best option.
The material used to manufacture a spectacle lens is classified by something known as its refractive index. For plastics lenses the refractive indices generally available include 1.5, 1.53, 1.6, 1.67 and 1.74. Glass lenses have refractive indices of 1.5, 1.6, 1.7, 1.8 and 1.9. You may have been told in the past that the higher the refractive index the thinner (and more expensive) the lens. This is not always the case! The thickness, weight and appearance of the finished lens will depend on many factors including the shape and size of the frame chosen, your own facial features, the specific type of lens and of course the refractive index of the lens material. At Andrew Keirl Opticians in Liskeard we have a clever gadget which traces the shape of the frame to be used. The lens and prescription information is entered into a computer programme along with the trace of the frame and the precise thickness and weight of the finished lens is calculated and an image of the lens displayed on the screen. You can actually see what you are getting! Using this technology we can provide you with the best advice possible which may not always be the most expensive option available.
Shatterproof lenses are now available for most lenses types and prescriptions. For certain frame types such as rimless and semi-rimless frames we supply shatterproof lenses as standard. Shatterproof lenses are also recommended for children and for those who require eye protection at work and at play.
If you need spectacles that will help you see clearly for both distance and near you no longer need to have a visible line across the lens. Varifocals are lenses that offer distance, intermediate and near vision in one lens! The power of the lens gradually changes to give distance vision at the top of the lens to reading vision at the bottom. Advanced varifocal lenses known as freeform lenses can now be individually designed to provide optimum performance for your individual needs. We will ask you a series of questions and using a computer programme come up with a lens designed specifically for you. In addition, the lens design will also take into consideration the fit of your chosen spectacle frame as a range of accurate measurements are taken which are also used in the calculation of the lens design. At Andrew Keirl Opticians in Liskeard we specialise in varifocal lenses and love to help patients who have had problems adapting to varifocals in the past. We also specialise in lenses that are designed for indoor use, for example, the home and office environment and lenses for specific hobbies and interests. These lenses are particular useful for computer users.
A reflection-free coating virtually eliminates reflections from the surfaces of a spectacle lens which can often be a cause of irritation to wearers. Reflections from the surfaces of a spectacle lens will reduce the quality of a patient’s vision and can cause specific visual problems when driving at night and when working in an office environment under artificial lighting. As the surface of the lens acts a bit like a mirror other people will notice these reflections instead of seeing the wearer’s eyes. Most reflection-free coatings are multi-purpose and offer other advantages such as improved water and condensation resistance, anti-fog, easy to clean and scratch resistance.
Standard scratch resistant lenses with a hard coating are also available which give protection from everyday wear and tear.
LCD and LED computer and television screens, smartphones, tablets and GPS devices all emit blue light, also known as high energy visible light. Although blue light in itself is a natural phenomenon, which is present in daylight and helps us to stay awake; over-exposure can have an adverse effect and cause eye strain, eye fatigue and even sleeplessness. A blue control coating applied to the surface of a spectacle lens neutralises the blue light emitted by digital screens, reducing the risk of eye fatigue and eye strain. It keeps the eyes in better condition, offering more comfortable and relaxed vision and a better contrast perception. For that extra bit of comfort in a digital world!
The risks of exposure to excessive levels of visible and Ultra-Violet are well known and it is important that these risks are considered when choosing a tinted lens or a lens to provide sun protection. Ultra-Violet (UV) radiation ranges from around 400nm to 200nm and is divided into three groups.
UVA 400nm – 315nm UVB 315nm – 280nm UVC 280nm – 200nm
The human eye naturally protects us from excessive bright light by reducing the pupil aperture. The cornea absorbs most UVB radiation and the crystalline lens absorbs most UVA. UVC is normally not considered an issue as it is absorbed by the ozone layer in the atmosphere.
When dark tinted lenses are worn, our pupils don’t react to bright light in the same way, so if the tinted lenses fail to adequately block or reduce the level of UV light entering the eye, damage may occur. It is therefore vital that any tinted lens incorporates an appropriate level of UV absorption.
Photochromic lenses and certain other clear lens materials provide good protection from UV. However, some lens materials require the application of an additional UV absorbing filter when a tint is ordered. Although some debate exists as to the exact boundary between visible light and UV it has become widely accepted to specify a UV absorbing filter of 400nm, commonly referred to as a UV400 filter. Activities that specifically benefit from UV protection include climbing and flying where UV increases by about 5% for every 1000 feet of altitude.
Spectacle tints are often considered to be a fashionable addition, but the functional applications of tints are far more important especially when they are used to enhance contrast for driving or sporting activities. Some examples are given below:
Benefits of tinted lenses
Colour Benefit Application Grey Neutral colour reproduction that tends not to distort the integrity of colours General sun protection Green/Grey Neutral colour reproduction with some contrast enhancement General sun protection, driving Brown/Amber Improves contrast and depth perception by filtering blue wavelengths but colours are distorted. Good in bright, hazy and overcast conditions Driving, sports (golf) Yellow Contrast enhancement in poor light Driving, cycling, Sports (tennis, shooting, flying) Orange Eliminates blue light to improve tracking of objects against a blue sky Clay pigeon shooting, skiing, hunting Red/Orange Contrast enhancement Fishing Red Contrast enhancement Fishing, clay pigeon shooting Violet Fashion tint but used for contrast enhancement in some activities Athletics
There are a number of ways of incorporating a tint into a spectacle lens. A lens that does not change colour when exposed to UV light (sunlight) is known as a fixed tint. Glass lenses with a fixed tint have the colour built into the lens itself whereas plastics fixed tint lenses are dyed with only the surface of the lens being tinted.
Photochromic lenses are lenses that darken when exposed to UV light and lighten when worn indoors. The original photochromic lenses were known as reactolite lenses and were only available in glass materials. Today the vast majority of photochromic lenses dispensed are made in plastics materials and are known as Transitions or Adaptive lenses. Photochromic lenses are very popular and are available in most lens designs including single vision, bifocal and varifocal. Most lens materials including thin, light and safer lenses are also available in photochromic options. Today’s photochromic technology is also much more responsive which means that time taken for the lens to change form light to dark to light is kept to a minimum.
Because photochromic lenses rely on the presence of UV light, historically their use was restricted primarily to the outdoors and many drivers say that photochromic lenses do not go dark enough inside a car. However a new generation of photochromic lens is available called Transitions Extra Active which is designed to darken behind the windscreen of a car. It is also suitable for night driving.
Tinted lenses that incorporate a polarising filter offer further benefits to the wearer in addition to a fixed tint or a Transitions lens. Polarised light is also known as glare and is the most distracting and uncomfortable type of light.
Most of the glare that we encounter comes from horizontal surfaces like wet roads, water and snow. Polarised lenses are set to an angle that blocks horizontally polarised light from passing through the lens, thus greatly reducing glare. Activities that benefit from polarised lenses include driving, sailing, skiing, fishing and flying. For more information on polarising lenses click on our sunglasses page.
Pale tints can be useful for indoor use, especially in office environments and other work places where natural daylight is poor, and fluorescent lighting is prevalent. Specialist tints like Vista Mesh have been developed to filter out the light which causes flicker created by fluorescent lamps. The use of such lenses has given visual relief to computer uses, migraine sufferers and night drivers.
With a combined experienced of over 50 years (!) the team at Andrew Keirl Opticians in Liskeard know their way around frames. One of our patients once said “even with their eyes shut they’d get it right”. Thankfully we keep ours open! At Andrew Keirl Opticians we stock a large range of quality designer frames, advanced materials, contemporary designs and a great basic frame range. Current designers include Stepper, Oliver Goldsmith, Ted Baker, Fendi and the new and exciting Koali range of spectacle frames.
When helping a patient to select a new frame we are confident that we can find a selection of frames that hit the mark leaving patients with the dilemma of choosing which one is the best. For patients who have difficulty seeing themselves without spectacles we will take a photograph of you to help you make that important decision. There are no time limits at Andrew Keirl Opticians in Liskeard and patients are encouraged to take as long as they like trying on the different styles. As getting it right is at the core of our business and after taking the initial measurements for your new frame we will carry out unlimited adjustments, tweaks and minor repairs to ensure that you get the most from your new spectacles. We also offer a free cleaning service using a special ultrasonic cleaner. It is important to us that you have the correct frames and lenses to suit your eyecare needs. The team at Andrew Keirl Opticians in Liskeard fully understand the importance of choosing fashionable and functional frames to suit your requirements.