Purchase this article with an account.
Luuk Franssen, Huawei Zhao, Henk A. Weeber, Kevin L. Waltz, Patricia A. Piers; Optical Performance of Toric IOLs with Different Wavefront Aberrations. Invest. Ophthalmol. Vis. Sci. 2011;52(14):6191.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
It has been shown that in order to predict the clinical performance of IOLs in cataract patients, simulations should be performed with eye models that mimic as closely as possible the physical characteristics of the representative population. In this study a physical eye model was developed to simulate the performance of eyes of cataract patients with significant levels of corneal astigmatism. Subsequently, the optical performance of 6 different toric IOL models was assessed using this physical eye model.
In this study, the corneas of 91 patients presenting for LASIK were studied retrospectively to determine the average corneal spherical aberration of patients with significant levels of corneal astigmatism (>1.0 D). A physical eye model was constructed that reflects the average measured spherical aberration and chromatic aberration and that is able to incorporate variable cylinder values. The wavefront aberration of 6 toric IOL models was measured using a wavefront sensor for a 4.5 mm pupil size. In addition to different lenticular spherical aberration values, these lenses are also made from 4 different types of materials with different chromatic dispersive properties. Polychromatic measurements provide the most accurate prediction of the clinical performance of an IOL under normal daily lighting conditions. Therefore through focus MTF was measured using white light in the physical eye model. The influence of pupil size on optical outcomes was demonstrated by performing measurements for 3, 4 and 5 mm pupil sizes. Differences in image quality were captured by recording images of the USAF target in white light, thereby simulating retinal images.
No significant difference was found between the corneal spherical aberration values of eyes with significant levels of corneal astigmatism (0.26 µm for a 6 mm corneal aperture size) and a standard cataract population (0.27 µm for a 6 mm corneal aperture size).As is expected, the largest differences in measured MTF levels and in the quality of the simulated retinal images were found for the 5 mm pupil size. At 50 c/mm these polychromatic MTF values range from 0.15 to 0.41. The differences in these measured values of MTF relate to the differences in the measured values of lenticular spherical aberration, which ranges from -0.18 µm to +0.09 µm, and to the chromatic dispersion of the different IOL materials.
Physiologically realistic physical eye models must be used when determining the impact of IOL design. In order to optimize the optical performance of toric IOLs, wavefront aberration and chromatic behavior must be considered.
This PDF is available to Subscribers Only