AIM: To evaluate the repeatability of central corneal thickness (CCT) measurement by entacam, and agreement of CCT measured by Pentacam and ultrasound pachymetry (USP) in Chinese myopia. Thereby investigate the possib...AIM: To evaluate the repeatability of central corneal thickness (CCT) measurement by entacam, and agreement of CCT measured by Pentacam and ultrasound pachymetry (USP) in Chinese myopia. Thereby investigate the possibility of Pentacam as a substitute for USP in CCT measurement before refractive surgery. The effects of corneal curvature measured by Pentacam on CCT were also evaluated. METHODS: One hundred and forty-eight right eyes of 148 individual with myopia were included in this study. Three successive Pentacam CCT measurements followed by 10 successive ultrasound pachymetry were carried out in the 148 eyes. Mean of CCT taken by each device was calculated for comparison. According to the CCT measured by USP, all the 148 eyes were divided into 3 groups: <520 mu m, 520-560 mu m, >560 mu m. For all eyes and each group the CCT obtained by Pentacam and USP were compared. Anterior corneal curvature of the 148 eyes was also adopted for correlation analysis with CCT obtained by ultrasound pachymetry. In addition, CCT measurement using 60 random selected Scheimpflug images was performed by 3 skilled investigators at different time, and this was repeated for 3 times by a forth investigator to assess repeatability of Pentacam CCT measurement using Scheimpflug images. RESULTS: Intraclass correlation coefficient (ICC) analysis revealed high intraobserver repeatability (ICC=0.994, F=158.60, P<0.001) for CCT measurement by Pentacam. The interobserver (ICC=0.998, F =494.73, P <0.001) and intraobserver (ICC=0.997, F=383.98, P<0.001) repeatability for Pentacam CCT measurements using Scheimpflug images were also excellent. There was high positive correlation between the CCT values measured by Pentacam and ultrasound pachymetry (r=0.963, P<0.001). Bland-altman plots showed that the Pentacam underestimate the CCT by 8.02 mu m compared with ultrasouond pachymetry.The differences between Pentacam and USP increased as the CCT readings by USP increased (Pentacam vs USP: slope=-0.04, P< 0.05). The 95% upper and lower limits of agreement between CCT values obtained from the two devices were +9. 33 mu m and -25.37 mu m. No significant association could be found between CCT and anterior corneal curvature. CONCLUSION: Inter- and intraobserver variability for CCT measurements by Pentacam was considerably below clinically significant levels. CCT of myopia obtained by Scheimpflug camera, Pentacam, were highly correlated to that by ultrasound pachymetry. However, the values obtained are not directly interchangeable between Pentacam and ultrasound pachymetry as the 95% limits of agreement are relatively wide. Pentacam can be a useful instrument for measuring CCT in candidates to refractive surgery in clinic.展开更多
目的：比较Pentacam、IOLMaster和A型超声测量仪测量前房深度（anterior chamber depth,ACD）的准确性。方法：观察性对照研究。对69例（138眼）近视患者由同一操作者分别使用Pentacam、IOLMaster和A型超声测量仪进行ACD测量,并对所得...目的：比较Pentacam、IOLMaster和A型超声测量仪测量前房深度（anterior chamber depth,ACD）的准确性。方法：观察性对照研究。对69例（138眼）近视患者由同一操作者分别使用Pentacam、IOLMaster和A型超声测量仪进行ACD测量,并对所得数据进行统计学分析。3种仪器的测量值一致性比较采用Bland-Altman检验,且用组内标准差及计算重复性系数来评价3种方法的重复性。结果：Pentacam,IOLMaster和A型超声测量仪测得ACD值分别为（3.77±0.24）、（3.73±0.23）、（3.69±0.22）mm。Bland-Altman分析显示,3种方法测量ACD的平均值一致性较好（Pentacam vs IOLMaster：Co A 0.04mm,Lo A-0.05-0.13mm;A超vs IOLMaster：Co A 0.04mm,Lo A-0.17-0.08mm;Pentacam vs A超：Co A 0.08mm,Lo A-0.06-0.22mm）。组内标准差及计算重复性系数显示3种方法测量ACD的重复性好（Sw=0.03、0.02、0.03;2.77 Sw=0.08、0.06、0.08）。3种仪器测量ACD值相互正相关（r=0.946,0.987,0.951,P〈0.001）。结论：Pentacam、IOLMaster和A型超声3种方法测量ACD的可重复性均很好、变异小、高度相关。Pentacam测得的ACD值稍大于A型超声,但由于3组数据可重复性好,变异系数小,故此差异没有重要的临床意义。展开更多
文摘AIM: To evaluate the repeatability of central corneal thickness (CCT) measurement by entacam, and agreement of CCT measured by Pentacam and ultrasound pachymetry (USP) in Chinese myopia. Thereby investigate the possibility of Pentacam as a substitute for USP in CCT measurement before refractive surgery. The effects of corneal curvature measured by Pentacam on CCT were also evaluated. METHODS: One hundred and forty-eight right eyes of 148 individual with myopia were included in this study. Three successive Pentacam CCT measurements followed by 10 successive ultrasound pachymetry were carried out in the 148 eyes. Mean of CCT taken by each device was calculated for comparison. According to the CCT measured by USP, all the 148 eyes were divided into 3 groups: <520 mu m, 520-560 mu m, >560 mu m. For all eyes and each group the CCT obtained by Pentacam and USP were compared. Anterior corneal curvature of the 148 eyes was also adopted for correlation analysis with CCT obtained by ultrasound pachymetry. In addition, CCT measurement using 60 random selected Scheimpflug images was performed by 3 skilled investigators at different time, and this was repeated for 3 times by a forth investigator to assess repeatability of Pentacam CCT measurement using Scheimpflug images. RESULTS: Intraclass correlation coefficient (ICC) analysis revealed high intraobserver repeatability (ICC=0.994, F=158.60, P<0.001) for CCT measurement by Pentacam. The interobserver (ICC=0.998, F =494.73, P <0.001) and intraobserver (ICC=0.997, F=383.98, P<0.001) repeatability for Pentacam CCT measurements using Scheimpflug images were also excellent. There was high positive correlation between the CCT values measured by Pentacam and ultrasound pachymetry (r=0.963, P<0.001). Bland-altman plots showed that the Pentacam underestimate the CCT by 8.02 mu m compared with ultrasouond pachymetry.The differences between Pentacam and USP increased as the CCT readings by USP increased (Pentacam vs USP: slope=-0.04, P< 0.05). The 95% upper and lower limits of agreement between CCT values obtained from the two devices were +9. 33 mu m and -25.37 mu m. No significant association could be found between CCT and anterior corneal curvature. CONCLUSION: Inter- and intraobserver variability for CCT measurements by Pentacam was considerably below clinically significant levels. CCT of myopia obtained by Scheimpflug camera, Pentacam, were highly correlated to that by ultrasound pachymetry. However, the values obtained are not directly interchangeable between Pentacam and ultrasound pachymetry as the 95% limits of agreement are relatively wide. Pentacam can be a useful instrument for measuring CCT in candidates to refractive surgery in clinic.
文摘目的：比较Pentacam、IOLMaster和A型超声测量仪测量前房深度（anterior chamber depth,ACD）的准确性。方法：观察性对照研究。对69例（138眼）近视患者由同一操作者分别使用Pentacam、IOLMaster和A型超声测量仪进行ACD测量,并对所得数据进行统计学分析。3种仪器的测量值一致性比较采用Bland-Altman检验,且用组内标准差及计算重复性系数来评价3种方法的重复性。结果：Pentacam,IOLMaster和A型超声测量仪测得ACD值分别为（3.77±0.24）、（3.73±0.23）、（3.69±0.22）mm。Bland-Altman分析显示,3种方法测量ACD的平均值一致性较好（Pentacam vs IOLMaster：Co A 0.04mm,Lo A-0.05-0.13mm;A超vs IOLMaster：Co A 0.04mm,Lo A-0.17-0.08mm;Pentacam vs A超：Co A 0.08mm,Lo A-0.06-0.22mm）。组内标准差及计算重复性系数显示3种方法测量ACD的重复性好（Sw=0.03、0.02、0.03;2.77 Sw=0.08、0.06、0.08）。3种仪器测量ACD值相互正相关（r=0.946,0.987,0.951,P〈0.001）。结论：Pentacam、IOLMaster和A型超声3种方法测量ACD的可重复性均很好、变异小、高度相关。Pentacam测得的ACD值稍大于A型超声,但由于3组数据可重复性好,变异系数小,故此差异没有重要的临床意义。
