Ashwin Pammal T, Shah Sunil, Pushpoth Sreekumari, Wehbeh Louai, Ilango Balasubramaniam
Birmingham and Midland Eye Centre, City Hospital, Birmingham, UK.
Cont Lens Anterior Eye. 2009 Apr;32(2):64-7. doi: 10.1016/j.clae.2008.07.006. Epub 2009 Jan 31.
The aim of the study was to precisely quantify the relationship between the central corneal points, namely the pupillary centre and the thinnest point in the central cornea, in terms of their thickness and location in healthy adults.
120 eyes of 60 healthy adult volunteers underwent pachymetry with a Scheimpflug imaging system (Pentacam). The thickness at the pupillary centre (Central Corneal Thickness, CCT) and the thickness at the Thinnest Central Corneal (TCC) point were measured. One eye of each patient was used to analyse the mean difference between CCT and TCC. Unpaired t-test (one tailed) was used to test significance and 95% confidence limits were used. The precise location of the TCC in relation to the corneal apex was measured using vector algebraic and trigonometric calculations.
The mean CCT was 520+/-33microm and the TCC was 515+/-36microm. The difference between CCT and TCC was found to be 5.57microm (0-15.9microm, 95% CI; P=0.1909). The TCC location was inferotemporal to the corneal apex in 58/60 (96.7%) of the right eyes and in 49/60 (81.7%) of the left eyes. The average vector location of TCC of both eyes was inferotemporal. This coordinate was found to lie 0.62mm (right eye) and 0.79mm (left eye) from the corneal apex subtending and angle of 45.5 degrees (right eye) and -10.9 degrees (left eye) from the horizontal.
The study has identified the parameters of TCC and its relationship to CCT in terms of the location and thickness. For clinical usage, they can be interchangeable as there is no significant difference between the two. The consistency in the (inferotemporal) location of the TCC merits further research in this regard to the development of corneal ectasia.
本研究旨在精确量化健康成年人中央角膜点（即瞳孔中心和中央角膜最薄点）之间在厚度和位置方面的关系。
60名健康成年志愿者的120只眼睛接受了Scheimpflug成像系统（Pentacam）的测厚检查。测量瞳孔中心的厚度（中央角膜厚度，CCT）和中央角膜最薄点（TCC）的厚度。每位患者的一只眼睛用于分析CCT和TCC之间的平均差异。使用未配对t检验（单尾）进行显著性检验，并使用95%置信区间。使用向量代数和三角计算测量TCC相对于角膜顶点的精确位置。
平均CCT为520±33微米，TCC为515±36微米。发现CCT和TCC之间的差异为5.57微米（0 - 15.9微米，95%置信区间；P = 0.1909）。在右眼的58/60（96.7%）和左眼的49/60（81.7%）中，TCC位置在角膜顶点的颞下方向。双眼TCC的平均向量位置在颞下方向。发现该坐标距离角膜顶点右眼为0.62毫米，左眼为0.79毫米，与水平方向的夹角右眼为45.5度，左眼为 - 10.9度。
本研究确定了TCC的参数及其在位置和厚度方面与CCT的关系。在临床应用中，由于两者之间无显著差异，它们可以互换使用。TCC（颞下方向）位置的一致性在角膜扩张症的发展方面值得进一步研究。
