Contact lens fitting after photorefractive keratectomy (PRK)
1 May 2001
Volume 02, Issue 2
This article looks at the development of more refined corneal topography measurements and algorithms based on past performance, and how they are helping to improve the predictability of PRK results.
Introduction
The refractive correction due to corneal surface ablation by excimer laser was named photorefractive keratectomy (PRK) by Trokel et al. (1983) and by Marshall et al. (1986). The lasers emit ultraviolet wavelengths of high proton energy capable of breaking intermolecular bonds within proteins and other large molecules without causing thermal damage. Since 1990, a large number of PRK studies have been carried out (Piebenga et al. 1993, Salz et al. 1993, Stevens et al. 1993, Tengroth et al. 1993). Early stage reviews included those by Stevens and Steele (1993) and by Lakkis and Brennan (1993). In 1991, for the low myopia range (up to -6.00D), unaided post PRK visual acuity (VA) of 6/12 (20/40) was obtained by 96% and VA of 6/6 (20/20) by 50% (Seiler & Wollensak 1991). Hamberg-Nystrom et al. (1994) found a more myopic result when using the VisX 20:20 system.
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