Bifocal and progressive contact lenses

Presbyopia tends to first affect people in their forties, when the ageing lens 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 can be affected, but it is often a simple, elegant solution to a complex issue.

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