Wavefront Analysis of the eye with Simultaneous Vision Bifocal Soft Contact Lenses with Transition Zone.

Abstract

Abstract: : Purpose: The purpose of this study is to investigate higher–order wavefront aberrations of the eye while wearing conventional bifocal soft contact lenses (BFSCLs) with two different types of optical design (a simple two–zone BFSCL–a and a three–zone BFSCL–b with transition–zone) and compared with those by monofocal soft contact lens (MFSCL). Methods: The BFSCLs were simultaneous–vision designs of concentric discrete power zones, the central optical zone for near view and the peripheral optical zone for distant view. The transition–zone were smoothly connected the central and peripheral optical zones. The subjects included 8 eyes of 4 presbyopic persons. Spherical equivalent refractive errors ranged from –9.25D to +1.00D (mean: –4.28D). Astigmatic values ranged from 0.00D to –1.50D (mean: –0.98D). We measured the higher–order wavefront aberrations with BFSCLs (additional power: +2.00D) and with MFSCL for far vision. Wavefront aberrations were examined with the Hartmann–Shack wavefront sensor (KR9000PW, Topcon Corp., Tokyo, Japan) for 4 mm diameter, and the ocular higher–order aberrations (OHA) up to 4th order (RMS error, µm) were calculated. Results: The total OHA with BFSCLs [BFSCL–a: 0.18±0.02 (mean±SD), BFSCL–b: 0.12±0.03] was significantly higher (p<0.01, One Way RM ANOVA) than that with MFSCL (0.09±0.01). In addition, total OHA with BFSCL–b was lower (p<0.01) compared with BFSCL–a. Especially, 3^rd–order aberration with BFSCL–b (0.10±0.03) was significantly lower (p<0.01) than that with BFSCL–a (0.14±0.02). Conclusions: The total OHA with BFSCL was higher than that with MFSCL but the insertion of transition–zone reduced the OHA, especially of 3^rd–order aberrations. These results suggest that the insertion of transition–zone is effective to improve the image quality of the eye with BFCLs.

Keywords: contact lens • optical properties