Safety and efficacy of undersurface ablation of the flap for regression after LASIK

• Main Authors: Ke-Li Long, Su-Yan Li
• Format: Article
• Language: English
• Published: Press of International Journal of Ophthalmology (IJO PRESS) 2014-06-01
• Series: Guoji Yanke Zazhi
• Subjects: cornea flap; undersurface ablation; laser <i>in situ</i> keratomileusis; regression; safety; efficacy
• Online Access: http://www.ies.net.cn/cn_publish/2014/6/201406038.pdf
• ISSN: 1672-5123; 1672-5123

AIM: To investigate the safety and efficacy of undersurface ablation of the flap(UAF)for laser <i>in situ</i> keratomileusis(LASIK)retreatment in eyes with regression.<p>METHODS: Twelve patients(22 eyes)with regression after LASIK were performed undersurface ablation of the flap. The mean of preoperative refractive error was -2.27±0.88D, the astigmatism was -0.44±0.30D, the central corneal thickness was 424.9±8.2μm. The follow-up time was 1a, including visual acuity, refractive error, the elevation of posterior cornea, WavScan. The data was analyzed with Student's <i>t</i> test and <i>χ</i>² test. <p>RESULTS:During the operation, the measured stromal thickness was 275.4±9.3μm, the flap thickness 144.7±7.5μm, the depth of ablation 28.1±9.3μm. The mean postoperative uncorrected visual acuity(UCVA)was 4.99±0.04, best corrected visual acuity(BCVA)5.03±0.04, at 1a follow up. There was no patient with postoperative BCVA decreasing, compared to preoperation. Mean spherical refraction decreased to -0.22±0.19 D at 1a follow up(<i>t</i>=10.232, <i>P</i><0.001)and the astigmatism decreased to -0.24±0.26 D(<i>t</i>=2.365, <i>P</i>=0.028). The elevation of posterior cornea changed from 1.95±1.68μm preoperatively to 2.00±1.88μm after 1a, but there was no statistical significance(<i>t</i>=0.090, <i>P</i>=0.929). The coma changed from 0.283±0.112μm preoperatively to 0.331±0.149μm after 1a(no statistical significance, <i>t</i>=1.452, <i>P</i>=0.161)and the spherical aberration changed from 0.320±0.119μm to 0.341±0.103μm(no statistical significance, <i>t</i>=0.390, <i>P</i>=0.674).<p>CONCLUSION:UAF, as one of a choice, is an effective and safe procedure for the treatment of regression after LASIK, based on the reasonable surgery design.