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Presbyopia is the reduction in near focusing ability resulting from the changes to the eye's crystalline lens. It is a natural consequence of aging, and most people begin to notice symptoms-- difficulty with small print, need for more light when reading, holding reading materials further away—around the age of 40.
For generations, patients relied on reading glasses or bifocals to provide clear near vision. But in the 1990's, many find these options limited and cosmetically unappealing. Monovision is another option to provide good near acuity without compromising appearance and comfort.
Monovision involves one eye, usually the dominant eye, being corrected for distance viewing, and the other eye being corrected for near viewing.
Monovision is actually a misnomer, since both eyes work together when viewing distance and near. When driving, for instance, the out of focus eye is slightly suppressed by the brain, but it still contributes important visual information regarding the periphery. This degree of teamwork between the two eyes will vary from patient to patient; therefore, a trial with monovision spectacles or monovision contact lenses is strongly advised before choosing monovision via refractive surgery.
Monovision does involve some degree of compromise. The most common complaints can be addressed as follows:
Visual fatigue or strain due to prolonged near work (such as needlepoint). Part-time reading glasses can be prescribed for the distance viewing eye.
Blurred vision may require part-time distance glasses to correct the reading eye.
Blurry intermediate vision, such as computer tasks, may benefit from part-time intermediate correction for both eyes.
Patients with monovision correction may notice flare, burn and glare with night driving. Again, part-time compensation driving glasses may be prescribed.
Monovision can be an excellent alternative to bifocal spectacles and current bifocal contact lens designs. The compromises associated with monovision seem to be more acceptable than a high degree of dependency on reading glasses.
You and your doctor can decide what is best for you by communicating your exact visual tasks, both occupational and recreational, and by participating in a monovision trial. Monovision collection is available through various refractive surgery techniques.