Characterization of optical performance with defocusing curve: Analysis of two refractive intraocular lens models with high and medium addition.

PURPOSE: To characterize the optical performance of two models of refractive bifocal intraocular lenses, with medium and high addition, using defocus curves.

METHODS: 20 eyes from 20 subjects were included in this study. 10 eyes underwent caratact surgery with an implant of a medium addition refractive bifocal intraocular lens (IOL) (Lentis LS-313 MF20) and the other 10 eyes underwent cataract surgery with an implant of a high addition refractive bifocal IOL (Lentis LS-313 MF30). Six weeks after surgery, subjective refraction and defocus curve were made.

RESULTS: Mean final residual refraction in spherical equivalent was +0.10±0.07D in the LS-313MF30 group and +0.12±0.10D in the LS-313MF20 group. Defocus curve showed a different optical performance in intermediate/near distance depending on the IOL model. The medium addition IOL provided good visual acuity (VA) at far and intermediate distance up to 50cms, and the high addition IOL provided better VA in near distance up to 25cms.

CONCLUSIONS: The high addition intraocular lens provides better visual acuity in the spatial range from infinity to the point close to 25cm. The medium addition intraocular lens provides excellent visual acuity in far and intermediate vision. The defocus curve seems to be a valid and reproducible tool for evaluating the optical behavior of multifocal sector refractive lenses.