Abstract
Purpose :
Pseudophakic chromatic aberration depends on material properties of the intraocular lens materials used. Spectral chromatic difference of refraction characterizes the wavelength dependence of longitudinal chromatic aberration (LCA). The purpose of this study was to explore the amount of ocular LCA of different IOLs when measured in vitro, as well as pseudophakic patients having different IOL designs implanted.
Methods :
Optical power measurements were made with an intraocular lens placed in a model eye on an optical bench. The model eye reproduced the spherical and chromatic aberration of an average pseudophakic eye: the Average Cornea Eye (ACE) model. Measurements were performed using a 3 mm aperture. The measurements were performed using wavelengths of 450, 500, 550, 600, and 650nm, respectively. LCA was expressed as the difference in optical power for the different wavelengths.
In a paired-eye pilot study, 23 patients implanted with IOLs representing two different materials (A and B) with different Abbe numbers were refracted. In addition to regular manual monocular refraction with a phoropter, the procedure was repeated after subsequently placing a blue and a red color filter in front of the patient’s eye. The difference in refraction represents the magnitude of chromatic aberration.
Results :
For the range of 450-650nm, the average LCA of the different lens designs was 1.47 diopter, and ranged between 0.75 and 1.78 diopter. The aphakic eye model had chromatic aberration of 1.04 diopter. For material A and B, the chromatic aberration was 1.3 D and 1.77D, respectively. In vivo measurements resulted in a difference in refraction between the blue and the red color filter. For IOL material A, the difference was 1.1 diopter, and for material B 1.3 diopter. The difference was statistically significant.
Conclusions :
In a physiologically representative chromatic eye model the chromatic aberration of IOLs can be measured well. LCA varies widely for different IOL materials. The results of the in vivo measurements confirm significant differences in chromatic aberration between different IOL materials.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.