角膜厚度对三种不同眼压计测量的影响

目的:比较采用Goldmann压平眼压计(Goldmann applanation tonometer,GAT)、非接触眼压计(non-contact tonometer,NCT)和Schiotz眼压计(Schiotz tonometer,ST)的眼压(intraoeular pressure,IOP)测量,评估角膜中央厚度(central corneal thickness,CCT)对读数的影响。方法:使用GAT、NCT和ST对所有患者的右眼进行眼压测量。超声角膜厚度测量法测定CCT。所有IOP及CCT测量由同一检查者进行。计算CCT25%(Q1)百分位数和75%(Q3)百分位数值,并通过这种方法将该组分为薄、中、厚角膜亚组。使用Statplus软件进行统计分析。结果:全系列144眼,GAT测量平均IOP为17.4±4.9mmHg,NCT为16.0±5.8mmHg,ST为14.0±4.0mmHg(Friedman方差分析P<0.01)。IOP水平和CCT之间的相关系数NCT为0.787(P<0.01),GAT为0.630(P<0.01),ST为0.565(P<0.01)。ST测量中,纠正的IOP误差和CCT之间的相关性在厚角膜明显弱(r=0.381,P=0.022)。结论:NCT是最易受不同CCT影响的设备。ST读数似乎比GAT和NCT读数受CCT的影响小。特别是在厚角膜,与NCT和GAT相比,ST可以被认为是一个更可靠的仪器。

Effect of corneal thickness on readings of three different tonometers

·AIM: To compare the intraocular pressure (IOP) measured by Goldmann applanation tonometer (GAT), non-contact tonometer (NCT) and Schiotz tonometer (ST), and to evaluate the effect of central corneal thickness(CCT) on the readings.·METHODS: IOP measurements were obtained in right eyes of all patients using GAT, NCT and ST. CCT was determinated by ultrasound pachymetry. All IOP and CCT measurements were performed by the same ophthalmologist. Percentile 25%(Q1) and percentile 75%(Q3) values of the CCT were calculated and by this way, the group was divided into thin, medium, and thick cornea subdivisions. Statistical analysis were performed with Statplus software.·RESULTS: For the entire series of 144 eyes, the mean IOPs measured were 17.4±4.9mmHg with GAT, 16.0±5.8mmHg with NCT, 14.0±4.0 with ST (P<0.01 Friedman ANOVA). Correlation coefficient between IOP level and CCT was 0.787 (P<0.01) with NCT, 0.630 (P<0.01) with GAT, and 0.565 (P<0.01) with ST readings. Correlation between deviation from corrected IOP level and CCT was remarkably weaker in thick corneas with ST measurements (r=0.381, P=0.022).·CONCLUSION: NCT is the most susceptible device to the effects of varying CCT. ST readings seem to be less affected than GAT and NCT readings. Particularly in thick corneas, ST can be defined as a more reliable instrument as compared to NCT and GAT.