title: An optical model to describe image contrast with bifocal intraocular lenses.
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.
authors.affiliation: Department of Ophthalmology, Beth Israel Hospital, Boston, MA 02215.
authors.forename: N H
authors.initials: NH
authors.lastname: Atebara
authors.forename: D
authors.initials: D
authors.lastname: Miller
mesh_terms: D015350:Contrast Sensitivity / Q000502:physiology*; D004867:Equipment Design; D007910:Lenses, Intraocular; D008953:Models, Anatomic; D008954:Models, Biological; D011680:Pupil / Q000502:physiology