Multifocal contact lenses are becoming a popular option for compensation of presbyopia, however they fail to provide usable multifocality in many patients, which is often attributed to lack of neural adaptation. We investigate optical quality with monofocal and multifocal contact lenses, the effects of contact lens design, corneal conformity, tear lens and ocular aberrations, and their impact on vision.
We found that semirigid contact lenses decrease corneal and total aberrations in most subjects. The comparison of internal aberrations with and without contact lenses allows the investigation of the effects of tear lens. (Dorronsoro et al. 2003).
We found that the natural aberrations of the eye and the conformity of the lens to the cornea are critical in the performance of multifocal contact lenses. We found that the design of the lens is altered on-eye by the conformity of the lens to the cornea, and as a result, in many cases no multifocal effect is shown (little differences with respect to monofocal lenses). In eyes with high positive spherical aberration inducing negative spherical aberration may actually result in increased performance in-focus and reduced depth-of-focus. (Dorronsoro et al.)