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AIM:To compare the refractive errors measured by the VISX WaveScan, OPD - Scan Ⅲ and the subjective refraction. METHODS: Seventy - six patients ( 152 eyes ) were recruited from January 2013 to December 2013. All patients were measured with subjective refraction by the phoropter (NIDEK, RT-5100), objective refraction by the WaveScan ( AMO Company, USA) , OPD-ScanⅢ ( Nidek Technologies, Japan). The sphere, cylinder, axis of the three methods were compared and analyzed. RESULTS: The sphere measured by WaveScan was lower than that by subjective refraction, the difference was 0. 13±0. 30D (t=3. 753, P0. 05). The value of the difference between WaveScan and subjective refraction was 5. 87o±6. 19o for the axis and the difference between OPD-Scan Ⅲ and subjective refraction was 3. 82o±3. 95o. There was statistic significance (t=2. 817, P=0. 006). CONCLUSION: For sphere and cylinder, WaveScan generated some deviation relative to subjective refraction. The Nidek OPD-ScanⅢ gives more accurate measures of objective refraction when compared with subjective refraction.
RESUMEN
AIM: To investigate the safety and efficacy of undersurface ablation of the flap ( UAF ) for laser in situ keratomileusis ( LASIK ) retreatment in eyes with regression. 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 t test andχ2test. 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 (t=10. 232, 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.