Lenses

If you have a new prescription or just want new specs, the optometrist at the end of your eye examination will introduce you to one of our dispensing opticians, explaining their findings and your particular needs.

The dispenser will then explain to you about different types of suitable lenses, possible coatings and prices and advise you on the most appropriate lens type for your visual and cosmetic requirements. Together, you can make an informed choice as to which lenses are right for you. Modern technology means that there are many options available, to ensure that your eyewear looks great and, of course, performs well visually. Lenses can be specifically for one task or they can be multifunctional, to wear all day. Whatever your requirements, we have the ideal lens for you. As an independent practice, we have access to spectacle lenses from the world’s top manufacturers. We dispense lenses made by Essilor, Nikon and Zeiss.
 
Single vision lenses...
…have one single prescription across their entire surface, correcting either myopia (short-sightedness), hyperopia (long-sightness) and/or astigmatism (distorted focussing).
 
Generally, people under 45 can manage with just one prescription and use it generally for distance or closer vision, but as our eyes age and our internal eye lens hardens, we lose the ability to quickly refocus from one distance to another (presbyopia). This then results in the need for either single vision lenses which are for only one task, e.g. reading or driving – so maybe 2 or 3 different pairs of spectacles become necessary for different tasks – or otherwise changing onto double or multifocal lenses.
Bifocals...
…are the solution when two different prescriptions are required, maybe for both distance and reading vision. Bifocals have two distinct optical powers – usually the top section for longer range and the lower section for closer range – and avoid the annoyance of having to swap two pairs of specs around.
 
They are very useful for multitaskers who like to watch TV and read / sew / knit at the same time or the car navigator who needs to watch the signs ahead and read the map. Their disadvantage is an obvious dividing line on the lens, between the two sections, which is not great cosmetically and can be rather disorientating when walking around.
Varifocals (Multifocals)...
…, also called Progressive Lenses, are the modern alternative to bifocals. Instead of just two optical zones, varifocals have a continual blend and increase in powers from the longer range distance areas at the top, to the stronger closer range zones near the bottom.
 
The primary advantage of varifocals over bifocals, apart from the obvious cosmetic advantage of not having a visible line across the lens, is that instead of just distance and near portions, intermediate zones are also catered for, although only in the specific sections of the lens along the central power corridor.
 
Varifocals can take a little while to adapt to, as the wearer has to learn the best head and eye angle for each area of the lens. Once adapted, they are an excellent lens for wearing generally. However, as more powers are included this can mean that the zone of best reading or computer vision may be quite narrow, so it can be useful to also have an extra pair of single vision specs for specific tasks such as reading in bed. There are good, better and best varifocals which prioritise certain sections for the lens – again our dispensing optician will advise you on the most appropriate lens for your requirements.

All spectacle lenses are a compromise. We cannot give an older person 20 year old eyes again. Progressive and bifocal lenses are both a compromise, in different ways. If dispensed for the appropriate reasons for each patient, they are excellent. However, if their design principles are not explained and if the patient chooses them for the wrong reasons, then they will be very disappointed. Our optometrist and dispenser will advise you on the best options for your needs. These lenses also need very accurate fitting, to ensure that the most appropriate section of the lens is in line with your eyes at each viewing position, so again this should be done by a member of our professional team. There are good, better and best designs of lenses which can be tailored to the individual’s requirements and budget.
Occupational lenses are bifocals or varifocals that are for specific working tasks, such as sitting at a desk all day, viewing the computer screen and reading written print. They are special because of the unusual placement of the near and intermediate zones in the lenses, to make certain tasks clearer and more comfortable. They are typically not suitable for every day wear. Historically, spectacle lenses were made from glass, but these had the disadvantage of being heavy and breakable. Whilst glass is still available today, the majority of spectacle lenses are made from lighter-weight, safer plastic materials.
 
About Lens Indices and Materials
Lens index refers to the density and refractive index of the lens material, which determines how thin the lens can be made – we recommend higher index lenses for higher prescriptions, to avoid the lens looking chunky. Lenses range from standard plastic (index 1.5) up to the very thinnest glass (1.9) – in simple terms, the higher the number, the thinner and flatter the lens can be made. There are good, better and best lens materials in both plastic and glass, making lenses not only thinner but also lighter, more comfortable and much better looking. Lenses can also be designed so that the front surface has an aspheric design, which is computer generated surface making the lens flatter and giving a thinner more cosmetic appearance.
 
The lens material that is best for you will depend not only on your prescription, but also the size and shape of your chosen frame, and our dispensing opticians will help you choose, so that you get the best results at the best price. Sometimes, there is little gained by going for the thinnest (and more expensive) material, so we will advise you accordingly.
 
Polycarbonate and Trivex materials are mid-index lenses with the greatest internal strength, making them the best lens materials for impact- resistance. They also offer& 100% protection against the sun’s harmful ultra-violet rays. Both are excellent materials for children’s eyewear and safety spectacles. Polycarbonate has the higher refractive index, so is the thinner of the two, but Trivex has the lower specific gravity, making it 10% lighter than Polycarbonate.
Photochromic lenses...
… are lenses that darken on exposure to specific types of light, most commonly ultraviolet radiation from the sun on bright days.
 
Once the light source is removed (for example by walking indoors), the lenses will gradually return to their clearer state. Photochromic lenses may be made of glass, plastic or polycarbonate. They are extremely useful for everyday wear as they quickly adjust and adapt to the current light conditions, helping you through your busy day. This dynamic lens type is designed to be worn both indoors and to automatically adapt when outdoors to give you a more comfortable viewing experience, while protecting your eyes from damaging UV light.
 
Some brands of photochromic lenses that we can dispense for you are Transitions, Sunsensors and Reactolite. As they do rely on exposure to UV for maximum reaction, photochromic lenses will not fully darken inside a car, so we recommend a separate prescription sunglass pair of specs for sunny, daytime driving, probably with polarised lenses.
Polarised lenses
… have two advantages: They are highly suitable as sunglasses and they neutralise uncomfortable reflections from wet roads, water surfaces and snow. The latter is referred to as glare, and eliminating it enhances contrast, allowing you to enjoy the surroundings in a relaxed, comfortable way. Polarised lenses offer 100% UVA and UVB protection, so are great for people with photo-sensitive eyes. We strongly recommend polarised lenses for fishing, skiing and driving.

Once you’ve decided on the most appropriate lens type and material, the dispenser will discuss lens coatings with you. Doubts may arise as to whether we should choose lenses with specific coatings or whether it is possible to manage without them. Rather than basing our decision solely on price, we should take into account our visual needs and understand that treatments can often offer significant advantages.
 
Anti-reflection coatings...
… can greatly improve the clarity of our vision. Usually a multi-layer treatment, anti-reflection coatings eliminate surface reflection from the spectacle lens, making it possible for more light to pass through, ensuring sharp, clear and high contrast vision. This treatment is usually combined with a water-repellent or an easy clean element, that repels rain and dirt and makes the lenses much easier to maintain. It is even possible to have a coating that stops your lenses fogging up (Opti-fog) when you change from one temperature environment to another, e.g. opening the oven or dishwasher, or stepping outside from an air-conditioned office in to the summer heat. Lenses that don’t have an anti-reflection coating may produce irritating light reflections working on a computer, when driving on wet roads or at night and are also apparent during face-to-face conversations.
Anti-scratch, hard coatings...
… make the lenses more resistant to knocks and scratches. These coatings are of most benefit to spectacles that are not worn full-time. The frequent on-off-on-off usage of part-time specs makes them especially prone to damage, so it is wise to protect the lenses with an anti-scratch, hard coating, to prolong their life. No treatment will be 100% effective against knocks and abrasions, however, if the lenses have been treated with a strengthening coat on both sides during the manufacturing process, they will be much more resistant to scratches which would otherwise interfere with your vision, in turn helping to ensure your specs last longer.

In summary, our dispensing optician will discuss your options and advise you, so that you can select the most appropriate lens for your prescription and your requirements.
Transitions lenses:

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