Cho Pauline, Cheung Sin Wan
Centre for Myopia Research, Department of Optometry & Radiography, The Hong Kong Polytechnic University, Kowloon, HKSAR, China.
Ophthalmic Physiol Opt. 2002 Nov;22(6):505-10. doi: 10.1046/j.1475-1313.2002.00060.x.
Two sets of corneal thickness (CT) measurements at five corneal locations were made with Orbscan on 33 normal young adults. No significant intravisit and intervisit differences at any of the corneal locations were found (Repeated measures ANOVA, F < 0.49, p > 0.49). The 95% limits of agreement (95% LA) for between-measurement differences for the central cornea was about +/-19 microm (or 3%), indicating good repeatability; for the inferior, temporal and nasal corneal locations, the 95% LA were close to +/-30 microm (approximately 4-5%); and for the superior corneal location, they were about +/-35 microm (or 5.5%). The estimated number of repeated measurements that should be taken for accurate CT measurements (at any of the five corneal locations and excluding outliers of >3 S.D.) of 2% (standard error) is < or =2, and of 3% is 1. This study shows that only central CT measurements with the Orbscan are repeatable. The role of the Orbscan pachometry is therefore limited and is recommended for central CT measurements only.
使用Orbscan对33名正常年轻成年人在五个角膜位置进行了两组角膜厚度（CT）测量。在任何角膜位置均未发现显著的测量内和测量间差异（重复测量方差分析，F < 0.49，p > 0.49）。中央角膜测量间差异的95%一致性界限（95% LA）约为±19微米（或3%），表明重复性良好；对于下角膜、颞侧角膜和鼻侧角膜位置，95% LA接近±30微米（约4 - 5%）；对于上角膜位置，约为±35微米（或5.5%）。对于准确的CT测量（在五个角膜位置中的任何一个且排除标准差>3的异常值），估计达到2%（标准误差）所需的重复测量次数≤2次，达到3%则为1次。本研究表明，使用Orbscan仅中央CT测量是可重复的。因此，Orbscan测厚仪的作用有限，仅推荐用于中央CT测量。
