A guide to explain the difference between Varifocal and Bifocal lenses and what they do.

Varifocal and Bifocal lenses are corrective lenses used in spectcales to correct presbyopia and other disorders of accommodation. They are characterised by a gradient of increasing lens power, added to the wearers correction for the other refractive errors. The gradient starts at a minimum, or no addition power, at the top of the lens and reaches a maximum addition power, magnification, at the bottom of the lens.

Varifocal Lenses

Varifocal lenses allow you to see near and far using just one pair of glasses. And unlike bifocals there's no visible line, just a smooth transition from near to far.

· Bifocals WITHOUT the visible lines
· Accurate blend of distance, middle and reading prescriptions.
· See clearly at all distances
· Look just like ordinary lenses

Bifocal Lenses

Two prescriptions in one lens. Whether you're reading a book, watching TV or driving, with bifocal lenses you only ever need one pair of glasses.

· Combination lens for both distance and reading
· No need for two pairs of glasses
· Choice of D-segment or full width divide

More info...

The length of the progressive power gradient on the lens surface is usually between 15 and 20 mm with a final addition power between 1.00 to 2.50 Dioptres for most wearers. The addition value prescribed depends on the level of presbyopia of the patient and is closely related to age. i.e Distance use at the top of the lens and reading use at the bottom of the lens.

Bearing in mind the lens provides a power that is best suited for distance viewing at the top and near viewing down the bottom of the lens, the wearer can then adjust the additional lens power required for clear vision at different viewing distances by tilting his or her head to sight through the appropriate part of the vertical progression. Further, since near vision tasks such as reading are usually low in the visual field and distant objects higher in the visual field, the lens location of the correct addition power for the viewing distance usually only requires small movements of your head.

We hope this guide has provided you with a better insight into the world of Varifocal and Bifocal lenses. If you are thinking of buying a new pair of glasses, see our other guides with provide advice and tips on all aspects of eyewear.

Thanks again
Designer Eyewear 4u Team.