Lenses

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.

Image courtesy of BBGR

Different postures for left- and right-handed people: Posture, and therefore the way we look through our spectacles, is different for left- and right-handed people. Using new technologies, BBGR have developed a varifocal lens which adapts to the postures of left- and right-handed wearers. If you’re considering varifocals, please ask our dispensers about BBGR Intuitiv lenses.

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 a computer-generated surface making the lens flatter and giving a thinner, more cosmetically appealing 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.

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.

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. 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 pair of prescription sunglasses for sunny, daytime driving – probably with polarised lenses.

Transitions Xtractive: Extra Protection from light, even in the car. These lenses have a permanent light tint which darkens when in light conditions – even when driving. They also work well even in the hottest conditions, while still blocking 100% of UVA and UVB rays.

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.

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 when you change from one temperature environment to another – e.g. opening the oven or dishwasher, or stepping outside from the 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.

VDU users: BBGR’s Neva Max Blue UV filters harmful blue light from VDU screens, enhancing contrast and reducing eyestrain.

Image courtesy of BBGR

The coating is 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.