An optical model to describe image contrast with bifocal intraocular lenses

Am J Ophthalmol. 1990 Aug 15;110(2):172-7. doi: 10.1016/s0002-9394(14)76987-9.

Abstract

We attempted to quantify the decrease in contrast associated with the concentric-style bifocal intraocular lens by using a model eye and bifocal intraocular lens, with a model unifocal intraocular lens as a control. When imaging near objects, pupils smaller than 2.5 mm produced image contrast of 100% of the control; larger pupils degraded contrast to 25% for a 6-mm pupil. For distant objects, pupils smaller than 2.5 mm produced image contrast of 70% to 95% because of the pinhole effect; larger pupils engaged the distance portion of the intraocular lens and maintain 80% contrast on average. Thus, the bifocal intraocular lens produced image contrast greater than 70% in all situations tested, except when imaging near objects with a pupil larger than 3.5 mm. The data suggest that image contrast is highly dependent on pupil size and object distance.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Contrast Sensitivity / physiology*
  • Equipment Design
  • Lenses, Intraocular*
  • Models, Anatomic
  • Models, Biological*
  • Pupil / physiology