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Optical performance of decentered bifocal contact lenses.

Authors
  • Woods, R L
  • Saunders, J E
  • Port, M J
Type
Published Article
Journal
Optometry and vision science : official publication of the American Academy of Optometry
Publication Date
Mar 01, 1993
Volume
70
Issue
3
Pages
171–184
Identifiers
PMID: 8483576
Source
Medline
License
Unknown

Abstract

Contact lenses frequently do not center over the pupil. The potential changes in optical performance introduced by poor centration of bifocal contact lenses have only been described previously from theoretical considerations. The present study measured the modulation transfer function (MTF) of rigid concentric-design refractive and rigid diffractive bifocal contact lenses with varying apertures and amounts of decentration. Decentration was shown to have a greater effect on the MTF of the refractive than on the MTF of the diffractive bifocals. The MTF of the refractive bifocals was related to the proportion of the aperture covered by the central optic zone (COZ). Unexpectedly, the MTF of the distance focus of the diffractive bifocal contact lenses was reduced at moderately high spatial frequencies. The practitioner should be aware of the effects of decentration of bifocal contact lenses.

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