What are bifocal contact lenses?

In the not too distant past people suffering from presbyopia or difficulties in reading small print close up had little choice when it came to eye-care. With this condition which comes on in middle age it tended to be bifocal glasses or nothing.

Luckily technology has moved on swiftly and today it's sometimes just a matter of deciding which type of bifocal contact lens is best for you.

Presbyopia tends to first affect people in their in their forties, when the ageing lens in the eye loses some of its elasticity. The result is that the eye has difficulty in switching easily between focussing on a near object (such as a restaurant menu) and a distant object (the waiter in the background). The only way to correct the problem is to provide the eye with two different prescriptions, either with a different strength lens in each eye (monovision contact lenses) or with simultaneous vision lenses.

Simultaneous vision lenses enable the eye to focus on near and distant objects at the same time by dividing the lens into two or more prescriptions, either gradually, as a series of concentric circles, or divided horizontally (as with traditional bifocals). It's then left up to the eye to ‘learn' which part of the lens to use at which distance, which it does remarkably quickly.

Monovision lenses typically take a little longer to get used to, but may be more effective for certain conditions. One of the main drawbacks of Monovision lenses is that, as each eye is focussing on a different depth, binocular depth perception is affected. Most eye-care professionals will offer free trial lenses so it's worth listening to their advice and experimenting before making a firm decision.

Bifocal contacts are now available as hard rigid gas permeable lenses and soft lenses, including daily disposable lenses.

© The Pink Fridge Online Magazine 2008 - Contact Lenses

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