Sahin Afsun, Basmak Hikmet, Yildirim Nilgun
Department of Ophthalmology Eskisehir, Eskisehir Osmangazi University Hospitals, Turkey.
J Glaucoma. 2008 Jan-Feb;17(1):57-61. doi: 10.1097/IJG.0b013e31806ab33e.
To find out the effect of central corneal thickness (CCT) and radius of the corneal curvature on intraocular pressure (IOP) measurements using rebound tonometer (RBT) and Tono-Pen in healthy schoolchildren.
IOP was measured with Tono-Pen and RBT, respectively, in 165 healthy schoolchildren with a mean age 9.8+/-3.1 (range: 7 to 12 y) years. Corneal radius of curvature (in mm) was determined using a keratometer before CCT and IOP measurements. CCT was measured using an ultrasonic pachymeter after all IOP determinations had been made. The effect of CCT, radius of the corneal curvature, and sex on measured IOP was evaluated by linear regression analysis.
The mean IOP readings were 17.47+/-2.7 mm Hg using Tono-Pen, and 16.81+/-3.1 mm Hg using RBT. Tono-Pen measured IOP values slightly greater than that of RBT (P=0.006). Mean CCT was found to be 561.37+/-33 microm. A significant association between measured IOP and CCT was found with each device (r=0.220 for the Tono-Pen, r=0.373 for the RBT; P=0.006 for the Tono-Pen and P<0.0001 for the RBT). The IOP increased 2.2 and 3.7 mm Hg for every 100-microm increase in CCT for the Tono-Pen and the RBT, respectively. The relation between IOP and CCT was not different for boys and girls. Mean radius of the corneal curvature readings was 7.68+/-0.41 mm (42.75+/-1.37 D) for both sexes. There was no significant relationship between either the mean corneal curvature readings, or CCT and IOP (r=0.02; P=0.4 for CCT and r=0.01; P=0.5 for IOP).
Both the Tono-Pen and RBT have a systematic error in IOP readings caused by its dependence on CCT. The CCT measurements should be considered to ensure proper interpretation of IOP measurements in children, like in adults. The corneal radius of curvature had no significant effect on measured IOP with each device.
探究中央角膜厚度（CCT）和角膜曲率半径对健康学龄儿童使用回弹式眼压计（RBT）和非接触眼压计测量眼压（IOP）的影响。
分别使用非接触眼压计和回弹式眼压计对165名平均年龄为9.8±3.1岁（范围：7至12岁）的健康学龄儿童测量眼压。在测量CCT和眼压之前，使用角膜曲率计测定角膜曲率半径（单位：毫米）。在完成所有眼压测定后，使用超声角膜测厚仪测量CCT。通过线性回归分析评估CCT、角膜曲率半径和性别对测量眼压的影响。
使用非接触眼压计测得的平均眼压读数为17.47±2.7毫米汞柱，使用回弹式眼压计测得的平均眼压读数为16.81±3.1毫米汞柱。非接触眼压计测量的眼压值略高于回弹式眼压计（P = 0.006）。平均CCT为561.37±33微米。使用每种仪器测量的眼压与CCT之间均存在显著相关性（非接触眼压计r = 0.220，回弹式眼压计r = 0.373；非接触眼压计P = 0.006，回弹式眼压计P < 0.0001）。对于非接触眼压计和回弹式眼压计，CCT每增加100微米，眼压分别升高2.2和3.7毫米汞柱。眼压与CCT之间的关系在男孩和女孩中无差异。两性的角膜曲率半径平均读数为7.68±0.41毫米（42.75±1.37屈光度）。角膜曲率平均读数、CCT与眼压之间均无显著关系（CCT的r = 0.02；P = 0.4，眼压的r = 0.01；P = 0.5）。
非接触眼压计和回弹式眼压计在眼压读数上均存在因依赖CCT而导致的系统误差。与成人一样，在儿童中进行眼压测量时应考虑CCT测量结果，以确保对眼压测量结果的正确解读。角膜曲率半径对使用每种仪器测量的眼压无显著影响。
