Corrective lenses are normally prescribed to correct the refractive errors of the eyes to give good visual acuity at distance (6 m). When presbyopia is present, a convex lens addition (bifocal power) may be included as part of the near correction to move the near focussing point back into the normal reading range (36 to 46 cm). The advantages gained by these corrections may be minimal, or even detrimental, to visual acuity at the intermediate range. A study was undertaken to determine the functional visual acuity of presbyopic individuals at the intermediate visual range with and without the best near and best distant vision corrections.
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