With age our sight worsens successively as part of a natural process called ageing sight reduction or presbyopia. Today there are three different ways of re-configuring presbyopia with the help of contact lenses. An eye care specialist can prescribe multi-focal lenses, bifocal lenses or correct vision using a technique called monovision.
Monovision has proven to be a cost-efficient and generally reliable technique for adapting customized contact lenses in the early stages of presbyopia. Simply stated, this form of visual correction provides the customer with a lens or laser surgical correction that re-configures the eye either for improved distance vision or for better near focus.
Allowing the dominant or "sighting" eye to play the lead in viewing distant objects, the optical specialist strives to correct the other eye in tandem so as to achieve best focus on near objects. When distance vision or near-sighting is very good in one eye, satisfactory monovision can often be achieved with the use of only one lens on the dominant eye for optimal farsighted correction or on the non-sighting eye for nearsighted focus. In the majority of cases, though, some refractive correction is required for both eyes to achieve satisfactory visual balance between the two eyes.
Adaptation to monovisual correction requires a sort of reprogramming of the brain's visual neural pathways. Thus, it can take some time before the brain has become accustomed to processing visual information so that the eyes can readily focus on far and near objects simultaneously.
Customers with relatively large differences in their far and near prescriptions, anisometropes, aren't well-suited to monovision since they can have difficulty with depth perception 3 An additional drawback of this treatment is eye strain that can result from intensive periods of near work.
3 Cornea and Contact Lens Usage, Position Paper on Monovision AAO