Modulation transfer function: Rigid versus foldable phakic intraocular lenses

PURPOSE: To study in a standard eye model the changes in modulation transfer function (MTF) of a monofocal intraocular lens (IOL) when a phakic IOL (pIOL) is placed in the anterior chamber, compare the MTFs of the rigid Artisan pIOL and foldable Artiflex pIOL, and evaluate the temporal evolution of the MTF of the foldable pIOL after the mechanical stress the pIOL undergoes when injected. SETTING: Fundacion Oftalmologica del Mediterraneo, Valencia, Spain. METHODS: The MTF values of the IOLs were calculated from the cross-line spread function recorded with the Opal Vector System. The measurements were taken using an eye model following the British and EN-ISO standards with 2.0 mm, 3.0 mm, 4.0 mm, and 5.0 mm pupils. A 28.00 diopter (D) Ophtec monofocal IOL was used as the crystalline lens. The 2 pIOLs were -9.00 D. RESULTS: The MTF of the rigid pIOL was slightly better than the MTF of the foldable pIOL with all pupil sizes. Both pIOLs provided good optics quality when compared with the monofocal IOL. The injection effect of the foldable IOL disappeared after 2 hours. CONCLUSIONS: The MTF of the monofocal IOL was slightly reduced with implantation of a negative pIOL in the anterior chamber. The rigid pIOL provided better optical performance than the foldable pIOL with all pupil sizes, as shown by the MTF values. The decrease in MTF caused by the mechanical stress on the foldable pIOL was nullified after 2 hours with no effect on optical quality.