三种仪器测量中央及周边角膜厚度的比较

Comparison of central and peripheral corneal thickness measured with three devices

目的比较眼前节分析仪(Pentacam Scheimpflug系统)、眼前节光学相干断层扫描仪(OCT)与A超角膜测厚仪三种仪器测量CCT及PCT的差异。方法收集2015年7月至2016年2月在广州医科大学附属第二医院屈光手术中心行角膜屈光手术术前检查的近视患者42例(42只眼)。每位患者分别用Pentacam、Visante OCT和A超三种仪器重复测量三次,读取角膜中央和距中央3.5 mm处上方、颞上方、鼻上方、下方、颞下方及鼻下方七个点处的角膜厚度值。三种方法测量CCT和PCT之间的角膜厚度采用单因素方差分析,组内两两比较采用LSD-t检验,不同测量方法之间的相关性采用Pearson相关性检验,不同测量方法的一致性采用Bland-Altman法检验。结果 Pentacam、OCT及A超测量的CCT平均值分别为(533.63±40.45)μm、(523.03±38.82)μm及(533.19±39.05)μm。经方差分析,差异无统计学意义(F=1.17,P>0.05)。A超-Pentacam、US-OCT及OCTPentacam三种仪器之间有明显相关性(r=0.977,0.985,0.992;P<0.05)。经一致性分析,结果 OCTA超、Pentacam-A超及Pentacam-OCT仪器测量差值及一致性界限上下值分别为(-10.60±6.95)μm(-24.22μm/3.01μm)、(-0.44±8.56)μm(-17.21μm/16.33μm)及(10.17±5.00)μm(0.37μm/19.96μm)。此外,距中央3.5mm处角膜厚度测量:三种仪器之间的差异性增大,相关性降低,一致性也降低。结论中央角膜厚度的测量,三种仪器之间有明显相关性和较好的一致性。周边角膜厚度的测量,三种仪器之间一致性较差,临床上三种仪器不能相互取代。

Objective To compare central（ CCT） and peripheral（ PCT） cornea thickness using Scheimpflug imaging（ Pentacam）,optical coherence tomography（ Visante OCT） and ultrasound pachymetry.Methods A total of 42 cases（ 42 eyes） with myopia were collected in the Second Affiliated Hospital of Guangzhou Medical University from which year which month to year which were examined by the refractive surgery center. In 42 eyes,corneal thickness was measured by Pentacam,Visante OCT and ultrasound pachymetry. The central cornea thickness（ CCT） and corneal thickness at 6 peripheral points（ 3. 5mm superior,uperotemporal,superonasal,inferior,inferotemporal,inferonasal） were evaluated. Differences of CCT and PCT were compared, the correlation and agreement between instruments were analyzed.Results Mean CCT readings of Pentacam,Visante OCT and ultrasound pachymetry were（ 533. 63 ± 40.45） μm,（ 523. 03 ± 38. 82） μm,（ 533. 19 ± 39. 05） μm. There were no statistically differences（ F = 1. 17,P 〉0. 05）. There was significant linear correlation between the 3 methods（ r = 0. 977,0. 985,0. 992; P〈 0.05）,especially between Pentacam and ultrasound pachymetry. The mean differences（ and upper / lower LOA） for CCT measurements were（- 10. 60 ± 6. 95） μm（- 24. 22μm /3. 01μm） between OCT and Amode ultrasound,（- 0. 44 ± 8. 56） μm,（- 17. 21μm /16. 33μm） between Pentacam and A-mode ultrasound,（ 10. 17 ± 5. 00） μm（ 0. 37μm /19. 96μm） between Pentacam and OCT. At the 6 peripheral points,the mean differences between instruments were higher,the correlation and agreement were lower than centrally. Conclusions Although the CCT measured by three measurements had high correlation and Pentacam had better agreement with A-mode ultrasound,as compared with OCT,important discrepancies among instruments exist. Good accuracy and agreement were noted for pachymetry measurements decreasing severely toward the periphery,these instruments should not be used interchangeably for PCT,the accurate assessment of the PCT needs more further research.