Aberrations of the tear-lens: soft contact lenses

摘要

Soft contact lenses (SCL) incorporating aberration-correction have the potential of providing acuity improvements beyond those offered by traditional spherical surface SCL. With the availability of such SCL offered by manufacturers, it is worthwhile to consider the extent of benefits such designs offer. One factor that can potentially influence the performance of aberration-corrected SCL is the optical effect introduced by the post-lens tear film (PoTLF). We modelled the optical impact of the PoTLF assuming three models: (1) worst case (2) representative Zernike surfaces, and (3) most-probable case. PoTLF parameters were based on measured or modelled values from previous studies. The optical contributions of the PoLTF was modelled as a pair of standard aspheric surfaces representing the posterior SCL surface and the anterior corneal/epithelial surface with r_0=7.80, k=-0.26. For each model, we analysed the MTF and calculated the Strehl ratio as a result of the optical aberrations introduced by PoTLF. Our results suggest that the PoTLF introduces a detectable amount of degradation in images and may slightly limit the visual benefits from aberration-corrected SCL. However, compared to the performance of traditional spherical surface SCL, we predict that worthwhile visual improvements should still be afforded by aberration-corrected SCL.