Prescription Lenses Explained
Unless you just want to buy the ‘frame only’ for your optician to fit your lenses, then you will need to select a lens type. There are three options; Single Vision, Bifocal and Varifocal.
Single Vision Lenses
Single vision lenses fall into three distinct usages:
These are most peoples’ first introduction to glasses, when the small print becomes just too small and lighting is never quite bright enough! As an alternative to arm extensions reading glasses will magnify anything inside 50 cms enabling clear vision close up. Outside of this distance things will start to blur, so watching tv whilst reading a book will mean peering over the top of your glasses to see the tv clearly, or you can choose one of the other lens options.
These are similar to reading lenses, but are a little weaker, giving them a longer focal range, extending, typically to arms length. This enables clear vision on your computer screen, or for reading music, where reading lenses might be too strong, forcing you to go closer to see clearly. These lenses may be just a fraction too weak to read small print with, so they tend to be quite specific in their use.
These lenses are for vision beyond arms length. Many people are able to use these lenses all the time, others may need a separate correction for close work. Distance lenses enable clear vision for driving, tv, and in many cases are worn all day.
Bifocal lenses, as the name suggest, incorporate two prescriptions in one lens, usually distance and reading, although other combinations are possible. Bifocals have a visible line separating the two sections, so cosmetically are inferior to varifocal lenses. They are, however, straightforward to use. They have a horizontal line separating the distance and reading sections, and the reading area is like a letter “D” on its side. The size of this reading segment can be varied to allow for an enlarged field of vision close up.
Varifocal lenses work in a similar way to bifocal in that the reading section is at the bottom of the lens, but they have no visible line, so they look like single vision lenses. This makes them cosmetically more appealing than bifocals. The prescription changes gradually from the distance at the top, to the reading at the bottom. This means they also have a section for intermediate vision (vdu/music). This makes them an excellent all round lens. There are hundreds of different designs of varifocal lens, but all work in a similar way.
Modern varifocal lens designs are called 'freeform back surface' varifocals, as the working part of the lens is on the back surface, rather than the front in older designs. This makes the usable part of the lens effectively wider as it is closer to the eye. The width of the intermediate and reading areas varies from design to design. Generally the better the quality lens (so the higher the price) the wider the usable areas, and the less distortion you see in the bottom corners. Therefore you should always choose the best lens you can afford to increase ease of adaptation.
Our varifocal lenses are separated into 3 categories to make it easy to choose:
- Standard Varifocals are traditional designs at affordable prices
- Premium Varifocals have a wider intermediate and reading area than standard lenses, with less peripheral distortion.
- Elite Varifocals are the latest design providing the maximum intermediate and reading width, with minimal peripheral distortion.
All our varifocal lenses are from Essilor and Kodak. If you have a specific lens preference please contact us for a price.