Abstract
Purpose: :
Some of the traditional aspheric contact lenses (T-CL) provide a better optical quality when they are well-centered on the cornea. However, the optical quality of the eye/CL system is deteriorated by lens decentation. We have developed a specially aspheric designed CL (S-CL) to improve the optical aberration in the eye/CL system even in the decentered position (Suzaki, et al, ARVO, 2007). In this study, we investigate higher-order aberrations (HOA) of the eye wearing two different types of optical aspheric designed CLs (T-CL and S-CL).
Methods: :
Fourty eyes of 20 normal subjects were studied. Eyes were classified into lens centration group (LCG) and lens decentration group (LDG). The aspheric hard contact lens (HCL) with a power of -4 diopter (D) and -10 D were used. The spherical refractive errors were corrected by glasses over the eye with HCL. Ocular HOA was examined with the Hartmann-Shack sensor (KR-9000PW, Topcon) for 4 mm diameter pupil, and calculated up to fourth-older (RMS error, µm). High- and low-contrast (100%, 10%) logMAR acuity (CSV-1000, Vector Vision) were measured as subjective parameters.
Results: :
In the LDG, the total ocular HOA with S-CL (0.18±0.12 µm) was significantly lower than that with T-CL (0.26±0.12 µm) when -10D lens was worn. Coma aberration by zernike vector analysis with S-CL (0.16±0.12 µm) was significantly lower than that with T-CL (0.19±0.15 µm). The mean axis of coma with S-CL (221.2°) and T-CL (216.5°) were the same as that of lens decentration on the cornea (S-CL: 205.7°, T-CL: 213.7°). In the LCG with -10D HCL and both in the LCG and LDG with -4D HCL, the total ocular HOA was not significantly different between with S-CL and with T-CL.
Conclusions: :
Specially designed aspheric HCL reduce the ocular HOA, mainly the third-order aberrations and may provide a better quality of vision compared with the traditional aspheric HCLs.
Keywords: contact lens • aberrations • visual acuity