chapter 9, Clinical Results of Wavefront-Driven Refractive Surgery

Excerpt

Over the past decade or so, laser vision correction technology has evolved from PRK to LASIK,[1, 2] from conventional treatment to wavefront-driven treatment,[3, 4] from no tracking to tracking and to faster tracking,[5, 6] and from no registration to registration. [7] At the same time, the laser repetition rate has increased significantly while the corneal heating is optimally controlled.[8] Consequently, the clinical results have become better and better, although the highly anticipated super vision[9, 10] has yet to come.

As discussed in the previous chapters, the science and technology for wavefront-driven laser vision correction are becoming more and more mature. We have explored how the ocular wavefronts are represented, how they are measured and reconstructed, how they are converted from one representation to another, how they are manipulated for geometrical transformations, how they propagate from one optical plane to another, and how they are evaluated with various optical metrics. They are treated with analytical theories that facilitate accurate and fast execution whenever needed. These theories give the surgeons and researchers a better understanding of the underlying technologies of wavefront-driven refractive surgery. They are also provided as tools for an evaluation of the potential benefits of such surgeries.

In this chapter, we discuss the clinical results for patients undergoing different treatment types with various refractive ranges. The emphasis is given to the wavefront-driven customized treatment, as it results in better clinical outcomes.[3, 4] The results are from various FDA clinical trials. Clinical parameters such as manifest refractions and visual acuities are reviewed. However, due to the inconsistency of data from FDA trials for different lasers, contrast sensitivity[11] and questionnaires[12, 13, 14] are not discussed.

9.1 Statistics of Ocular Aberrations

Human eyes exhibit refractive errors including low-order and high-order ocular aberrations. Thomas Young[15] was credited as the first to discuss the spherical aberration. Measurement of high-order ocular aberrations was started long ago. Koomen et al.[16] gave a historical account for the measurement of spherical aberration up to the first half of the 20th century.