Contrast attenuation characteristics of iris clipped intraocular lens implants in situ.

In this study contrast thresholds were monitored over a wide range of spatial frequencies for patients with iris clipped implants or Fyodorov and Binkhorst types. These results were compared with those of an age matched normal group and attenuation characteristics derived for the implants and media environment alone. These results show that lenticular implants of this type can produce large reductions in contrast with a wide variety of transfer functions, for example, low pass, band reject, and band pass. These findings highlight the potential inadequacies of the assessment of the visual capabilities of these devices by acuity measures alone. We suggest that a more realistic and abbreviated approach should be based upon supplementing acuity assessment with monitoring of threshold sensitivity for a low, medium, and high spatial frequency sinewave grating.