Abstract

SA.17.05

How do wavefront measurements influence, modern corneal and intraocular refractive surgery?

Koch D. D.
Houston, USA

Wavefront technology has transformed our understanding of human vision and the procedures that alter the optics of the human eye. Wavefront technology has enabled us to measure the optical properties of the cornea and crystalline lens, to study the impact of aberrations on quality of vision, and to understand the changes in the optical properties of the eye that occur with ageing, surgery, and other circumstances. In the field of corneal refractive surgery, wavefront-guided ablation has become the predominant treatment modality. Clinical results show improved accuracy, reduction in aberrations or in the magnitude of induced aberrations, and improved quality of vision as measured by contrast sensitivity and subjective questionnaires. Importantly, wavefront technology has demonstrated superior results in treating highly aberrated eyes, such as those that have undergone corneal transplantation or prior refractive surgery. Limitations of wavefront-guided corneal ablation include limited ability to selectively alter higher order aberrations and, in highly aberrated eyes, difficulty in acquiring adequate measurements and often incomplete reduction of higher order aberrations in those eyes that can be treated. For the latter group, corneal wavefront-guided aberrations show good promise.
In the field of cataract surgery, wavefront technology has primarily dealt with the issue of spherical aberration and its reduction through the use of intraocular lenses with negative asphericity. Although data are conflicting, most clinical trials show improved quality of vision in eyes implanted with these lenses. Much further work is required to develop methods for treating other higher order aberrations and for controlling the limitation induced by IOL decentration relative to the line of sight. Ultimately, some form of postoperative modification of the lens optic may prove to be the optimal approach.
A major limitation of wavefront technology is an understanding of how various aberrations affect quality of vision, particularly with regard to depth of focus. The ultimate goal is to be able to determine the pattern of higher order aberrations that provides the best quality of vision for an individual patient and to be able to modify the optics of the eye on an ongoing basis in order to adjust for age-related changes.

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