Department of Vision Sciences, Glasgow Caledonian University, Glasgow, United Kingdom.
J Cataract Refract Surg. 2009 Dec;35(12):2127-35. doi: 10.1016/j.jcrs.2009.07.012.
To compare corneal thickness measurements obtained by a slit-scanning method with those obtained by noncontact specular microscopy, with a focus on the midperipheral (3.0 mm) region of the cornea.
Department of Vision Sciences, Glasgow Caledonian University, Glasgow, United Kingdom.
In adults with up to 8.50 diopters of myopia, single measurements of corneal thickness were performed with specular microscopy (Topcon SP-2000P) at central, 3.0 mm nasal, and temporal midperiphery locations. Slit-scanning pachymetry (Orbscan II) measurements were then taken and data extracted for 2.0 mm diameter sample zones at the central, 3.0 mm nasal, and temporal locations.
The mean corneal thickness by specular microscopy was 0.524 mm in the central zone, 0.586 mm in the temporal location, and 0.547 mm in the temporal location. The mean uncorrected slit-scanning pachymetry readings were 0.584 mm, 0.668 mm, and 0.658 mm, respectively, and the mean 0.92 acoustic factor-corrected readings, 0.538 mm, 0.614 mm, and 0.603 mm, respectively. At central locations, the corrected slit-scanning measurements agreed with specular microscopy measurements to within +/-0.014 mm (95% confidence interval, -0.019 to +0.045 mm). However, even with correction, discrepancies at the midperipheral locations were as high as 4 times greater (temporal).
Results show that the slit-scanning pachymeter can substantially overestimate more peripheral thickness measurements of the cornea than specular microscopy or ultrasound pachymetry and that the differences cannot be corrected using the same acoustic factor (0.92). Off-center slit-scanning thickness measurements, therefore, cannot be used interchangeably with those obtained with other pachymetry methods, especially before refractive surgery.
比较角膜厚度测量的裂隙扫描法与非接触镜面反射显微镜，重点是角膜的中周边（3.0 毫米）区域。
格拉斯哥喀里多尼亚大学视觉科学系，英国格拉斯哥。
在近视不超过 8.50 屈光度的成年人中，使用镜面反射显微镜（Topcon SP-2000P）在中央、3.0 毫米鼻侧和颞侧中周边位置进行单次角膜厚度测量。然后进行裂隙扫描眼压计（Orbscan II）测量，并从中提取中央、3.0 毫米鼻侧和颞侧位置 2.0 毫米直径样本区的数据。
镜面反射显微镜测量的角膜平均厚度为中央区 0.524 毫米，颞侧 0.586 毫米，颞侧 0.547 毫米。未经校正的裂隙扫描眼压计读数分别为 0.584 毫米、0.668 毫米和 0.658 毫米，分别为平均 0.92 声速校正读数 0.538 毫米、0.614 毫米和 0.603 毫米。在中央位置，校正后的裂隙扫描测量值与镜面反射显微镜测量值的差异在 0.014 毫米以内（95%置信区间，-0.019 至+0.045 毫米）。然而，即使经过校正，中周边位置的差异高达 4 倍（颞侧）。
结果表明，裂隙扫描眼压计可大大高估角膜更周边的厚度测量值，超过镜面反射显微镜或超声眼压计，并且无法使用相同的声速（0.92）进行校正。因此，偏心裂隙扫描厚度测量值不能与其他眼压计方法获得的值互换使用，尤其是在屈光手术之前。
