An exploration of modified monovision with diffractive bifocal contact lenses

M. H. Freeman, W. N. Charman

    Research output: Contribution to journalArticlepeer-review

    Abstract

    A group of eight presbyopic subjects wore in succession four types of correction. One of these (A) consisted of a conventional pair of diffractive bifocals in which equal amounts of light contributed to the distance and near images in both eyes. Two (B and C) were modified monovision corrections using non-standard diffractive bifocal lenses. The diffractive designs were such that in the dominant eye a greater fraction of light was sent into the distance image and less into the near image and in the non-dominant eye a greater fraction contributed to the near image. The last lens combination (D) was a conventional monovision arrangement, with a single-vision distance correction on the dominant eye and a single-vision near correction on the non-dominant eye. Monocular and binocular high-contrast acuity, contrast sensitivity and stereopsis were assessed at both distance and near with each of the four lens combinations. It was hoped that the modified monovision arrangements (B and C) might yield improved distance and near acuities in comparison with the standard diffractive bifocals (A) while still maintaining good stereopsis in comparison with the single-vision monovision combination (D) and thus allow wearers to achieve better all round visual performance. Although these expectations were at least partly fulfilled, the modest advantages offered by the diffractive modified monovision approach did not appear to compensate for the disadvantages of its greater complexity. © 2007 British Contact Lens Association.
    Original languageEnglish
    Pages (from-to)189-196
    Number of pages7
    JournalContact Lens and Anterior Eye
    Volume30
    Issue number3
    DOIs
    Publication statusPublished - Jul 2007

    Keywords

    • Contrast sensitivity
    • Diffractive bifocals
    • Monovision
    • Stereopsis
    • Visual acuity

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