Modulation transfer functions of eyes implanted with intraocular lenses

An experimental study of the retinal image quality in aged subjects after their eyes have been implanted with intraocular lenses (IOL's) has been performed. The method is based on recording in vivo the aerial image of a point test, after a double pass through the ocular media, and subsequent computation of the eye's modulation transfer function. The optical performance of three different types of bifocal IOL is compared with that of conventional monofocal IOL's. The results show that eyes implanted with bifocals exhibit a mean reduction in the modulation transfer function (contrast in the retinal image) of a factor of 2, while keeping a resolution similar to that of monofocal IOL's (which explains why visual acuities are also similar in these two cases). The mean retinal image modulation in eyes implanted with monofocal IOL's is ∼2.5 times lower than that obtained with young emmetropic subjects, but it seems to be similar to that corresponding to # of persons of the same age (∼60 years) normal eyes.