ABSTRACT
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.
ABSTRACT
PURPOSE: To predict the accuracy of preoperative refractive error measurement methods in wavefront-guided laser-assisted subepithelial keratectomy (LASEK) surgery and to formulate a nomogram for satisfactory surgical results. METHODS: The medical records of 30 patients (57 eyes) who had undergone wavefront-guided LASEK were reviewed. The ideal surgical ablation amount was defined as the sum of the real surgical ablation amount and the remaining refractive errors. Comparison between the ideal surgical ablation amount and preoperative refractive errors was made using autorefraction, manifest refraction, cycloplegic refraction, postcycloplegic refraction, wavescan, and iTrace aberrometer measurements. RESULTS: The refractive errors measured by the postcycloplegic refraction showed the closest relation with the ideal surgical amount, and the nomogram based on this refraction correlated statistically significantly with the ideal surgical ablation amount. The refractive error using the wavescan also showed more accurate refractive measurements than the autorefractor and iTrace aberrometer. CONCLUSIONS: Accurate manifest refraction immediately before surgery is the most important in determining the ablation amount. Additionally, the refractive errors measured with the wavescan, which is an aberrometer used for wavefront-guided LASEK, showed a minimal amount of errors. After reviewing the results, the nomogram based on these 2 methods can be concluded to possibly contribute to an increase in the accuracy of surgery.