Abstract
Purpose: :
Clinical data shows that, when patients are implanted with multifocal IOLs, the subjective appearance and level of bother varies per patient. This may be partly due to the fact that each patient has different corneal aberrations. The purpose of this study is to explore the influence of corneal aberrations on the subjective appearance of halos obtained with multifocal IOLs.
Methods: :
In the current study, retinal images of extended light sources are simulated in computer-based eye models. The corneas of the eye models are based on measured data from cataract patients. They include higher order aberrations, as well as residual lower order aberrations. These models were then implanted with a bifocal intraocular lens. The point spread function of the eye is convolved with an extended light source, resulting in a retinal light intensity profile. Features of the retinal light intensity profile were correlated with the corneal aberrations.
Results: :
The retinal light intensity profiles represent a wide variety of halo appearances. The size of the halo (area) varied by a factor of 3 due to differing cornea aberration profiles. The area of the halo tended to be correlated with the RMS of the higher order corneal Zernike aberration, although this was not statistically significant (p=0.1). The images reveal very specific features, such as elliptical shapes, and eccentric areas of increased light intensity. Eye length and total optical power of the eye did not correlate with the appearance of these features.
Conclusions: :
The size, shape and intensity of the multifocal halo vary with each eye. The images suggest that corneal aberrations have a significant effect on the appearance of halos on the retina.
Keywords: intraocular lens • aberrations • refractive surgery: optical quality