Monovision Achieved with Excimer Laser Refractive Surgery

Presbyopia refers to the decrease in accommodative capacity that accompanies aging. By definition, presbyopia occurs when an individual’s accommodative power is no longer able to allow for sustained and comfortable near-vision work. The appearance of presbyopia is not defined by age or precise accommodative reserve, as people’s near-vision requirements differ. However, most people in their early forties begin to notice difficulties with performance of near-vision tasks. The presbyopic population in the United States is expected to double every 5 years until the year 2010. Monovision constitutes one means of addressing the problem of presbyopia. In monovision, one eye is optically corrected for distance vision and the other eye for near vision. The near-vision eye may be placed in focus at a reading distance (33 cm) or at an intermediate distance (for example, at 50 cm for computer use). The monovision approach has been successfully applied to presbyopic contact lens wearers. For contact lens wearers, single-vision contact lenses correct one eye for distance and undercorrect the other eye by 1 to 2 D. Refractive surgical procedures such as photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) serve to correct myopia by flattening the corneal curvature. The number of refractive surgery cases performed on a yearly basis continues to increase exponentially. Many refractive surgery patients are in the presbyopic or prepresbyopic age group, and these patients often experience difficulties with near vision