Abstract
Purpose::
Traditional contact lenses (T-CLs) are designed by considering the optical quality of the lens itself. More recently, some new CLs (N-CLs) 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 designed CL (S-CL) to improve the optical aberration in the eye/CL system even in the decentered position. In this study, we examined the optical aberrations induced in the eye/CL optical system by a S-CL and compared with those induced by T-CL and N-CL when the lenses were centered (on-axis) or decentered (off-axis) with respect to the pupil center.
Methods::
The higher-order aberrations (HOA) of the eye/CL system induced by the T-CL, N-CL and S-CL with different front curve eccentricities when fitted on- and off-axis were evaluated. Optical aberrations were calculated by ray-tracing in a model eye/CL system (CL/tear/Gullstrand model eye) using specialized software (ZEMAX: ZEMAX Development Corporation, WA, USA).
Results::
On-axis spherical aberration induced by the N-CL was reduced compared to the T-CL. However, the reduction in aberrations with the N-CL depends on the amount of lens decentration and third-order aberrations increased (0.40µm) when the lens was off-axis. In contrast, the S-CL showed a large reduction in HOA (0.08µm) compared with N-CL (0.40µm) when the lens was decentered (10 deg), mainly due to the reduction of thired-order aberrations. The spherical aberration with S-CL increased at on-axis, however, the absolute value of spherical aberration (0.08µm) was similar to that reported in normal human eyes (0.10µm).
Conclusions::
The reduction in off-axis HOA with the specially designed CL was mainly due to a reduction in third-order aberrations and is likely to provide better on-eye optical performance compared to traditional or new CL.
Keywords: contact lens • contrast sensitivity • visual acuity