Ocular Surface and Contact Lens Research Laboratory, University of Santiago de Compostela, A Coruña, Spain.
Eye Contact Lens. 2011 Nov;37(6):348-53. doi: 10.1097/ICL.0b013e3182323dcf.
To evaluate the effect of an acoustic factor (AF) on the comparison of central corneal thickness (CCT) and peripheral corneal thickness (PCT) measurements with Orbscan II and Pentacam.
The CCT and PCT at 1, 2, and 3 radial distances from the corneal apex were measured using Orbscan II and Pentacam in 22 right eyes of 22 healthy adults (7 men, 15 women). Three measures were obtained from each 1 of the 25 points measured and then compared to gauge the agreement between both devices at the corneal center and anular areas located at 1-, 2-, and 3-mm distances from the central measurement. Orbscan II readings were considered with and without an AF correction.
Pentacam provides statistically significant higher values than Orbscan II does at all the 25 locations analyzed (P<0.001). With a few exceptions, the average difference was fairly constant between 20 and 40 μm for all the corneal locations. A high correlation existed between central readings (r(2)=0.927; P<0.001) and average thickness at each one of the annular areas being analyzed (r(2)=0.897 at 1 mm, r(2)=0.876 at 2 mm, and r(2)=0.870 at 3 mm); Pentacam minus Orbscan II value averaged for all the points changed from -28±10 to -22±9 μm after the removal of the AF in Orbscan II.
Central and peripheral measurements of the corneal thickness obtained with Orbscan II and Pentacam are significantly different. The removal of the AF in Orbscan II renders lower mean differences but decreases the agreement between both systems and potentially induces an overestimation of CCT and PCT by Orbsan II compared with Pentacam.
评估声学因素（AF）对 Orbscan II 和 Pentacam 测量中央角膜厚度（CCT）和周边角膜厚度（PCT）的影响。
对 22 名健康成年人（7 名男性，15 名女性）的 22 只右眼进行 Orbscan II 和 Pentacam 测量，分别在角膜顶点 1、2 和 3 个放射距离处测量 CCT 和 PCT。从 25 个测量点中的每一点测量 3 次，然后进行比较，以评估两种设备在角膜中心和距中央测量点 1、2 和 3mm 的环状区域的一致性。考虑了 Orbscan II 读数是否带有 AF 校正。
Pentacam 在所有 25 个分析位置的测量值均明显高于 Orbscan II（P<0.001）。除了少数例外，所有角膜位置的平均差异在 20 到 40μm 之间相当稳定。中央读数之间存在高度相关性（r²=0.927；P<0.001），以及分析的每个环状区域的平均厚度之间存在高度相关性（在 1mm 处 r²=0.897，在 2mm 处 r²=0.876，在 3mm 处 r²=0.870）；在去除 Orbscan II 中的 AF 后，Pentacam 减去 Orbscan II 的平均值从所有点的-28±10μm 变为-22±9μm。
Orbscan II 和 Pentacam 测量的角膜中央和周边厚度存在显著差异。在去除 Orbscan II 中的 AF 后，平均差异会降低，但会降低两种系统之间的一致性，并可能导致 Orbscan II 对 CCT 和 PCT 的估计值高于 Pentacam。
