Clinical results of multizone photorefractive keratectomy for high myopia: Comparative study of two-zone and three-zone technique

Lee, Yong Jae; Oh, Sei Yeul; Kim, Woo Jung

Abstract

In order to reduce a depth and slope of edge of ablation, the technique using 2 or 3 ablaiton zones has been applied to excimer laser photorefracitve keratectomy (PRK) for high myopic patients. In this study, excimer PRK using 2 zones (5.0mm; 100%, 6.0mm; 70%) or 3 zone (5.0mm; 100%, 5.5mm; 70%, 6.0mm; 50%) were used to each 10 patients having a range of refractive power between -8D and -9.5D randomly and divided into group 1 and group 2, respectively. corneal epithelial healing was delayed in group 2 comparaed to group 1 and the diference of that between group 1 and group 2 were statistical significant (P<0.05). However, the difference of spherical equivalent between group 1 and group 2 was not statistically significant at each follow-up (p>0.05). Uncorrected visual acuities of 20/40 or better were achieved in all patients of both groups at the last postoperrative visit (mean+/-SD, 22+/-3.4 weeks). Spherical equivalent less than 1.0 diopter was achieved in 60% of group 1 and 80% of group 2. As a complication 3 eyes (30%) in group 1 and 1 eye (10%) in group 2 lost 2 lines of best corrected visual acuity and thee was no statistically significant difference in both corneal haziness and patients' complaints between group 1 and group 2. With these results we could find a similar clinical results between excimer PRK using 2 zones and 3 zones by 6 months.