Liu Li-Fang, Huang Chu-Kai, Zhang Ming-Zhi
Joint Shantou International Eye Center of Shantou University and the Chinese University of Hong Kong, Shantou 515041, Guangdong Province, China.
Int J Ophthalmol. 2014 Dec 18;7(6):930-4. doi: 10.3980/j.issn.2222-3959.2014.06.03. eCollection 2014.
To assess the repeatability and reproducibility of Tonolab tonometer in rats with high intraocular pressure (IOP) and evaluate its ability to detect IOP changes in rats with general anaesthesia.
Left eyes of adult Fischer rats (F344) were photocoagulated by 532 nm diode laser to induce high IOP. Hypertensive eyes of 30 conscious rats were randomly chosen to measure IOP on a single occasion. Two observers independently and alternately undertook IOP measurements consecutively for three times using the same Tonolab tonometer blind to the other observer's IOP measurements. The within subject standard deviation (Sw), coefficient of variation (CVw) (100×Sw/overall mean), and intraclass correlation coefficient (ICC) were calculated to evaluate intra-observer repeatability. Inter-observer difference was analysed by using 95% limits of agreement described by Bland-Altman and paired sample t-test. Also, another 13 normal F344 rats were intraperitoneally administrated with ketamine/xylazine or chloral hydrate, and IOPs of both eyes were measured by a single operator once every 5min until animals came to conscious. IOPs at various time points were compared by using one-way ANOVAs.
Mean IOP was 35.58 mm Hg (range 17.33 to 65.33 mm Hg). For intraobserver repeatability, the Sw, CVw and ICC of high IOP for two observers were 5.20 mm Hg/3.41 mm Hg, 9.98%/8.08% and 0.820/0.928 respectively. The inter-observer difference was 14.76%±19.76% of the mean IOP of two observers, with a 95% limits of agreement -23.97% to 53.50%, and the difference between mean IOP of these two observers was statistically significant (P=0.001). IOPs dropped slightly during the first 15min post-aneathesia, with a IOP change between 0.17 and 1.17 mm Hg. IOPs changed from basline of 11.75±2.05 mm Hg (n=12) to 8.75±1.06 mm Hg 20min post-anesthesia (P=0.001), and this hypotensive condition persisted until 80min post-anesthesia.
In this sample of hypertensive rats, Tonolab measurements demonstrated high levels of intraobserver repeatability, however, its interobserver reproducibility was poor. Longitudinal changes of IOP caused by genral anaesthesia can be sensitively detected by Tonolab. So we suggested that measurements of IOP using Tonolab are best measured by a single observer, and it could be included in experimental glaucoma.
评估托诺拉眼压计在高眼压大鼠中的重复性和再现性，并评估其在全身麻醉大鼠中检测眼压变化的能力。
成年Fischer大鼠（F344）的左眼用532nm二极管激光进行光凝以诱导高眼压。随机选择30只清醒大鼠的高血压眼进行单次眼压测量。两名观察者独立且交替地使用同一台托诺拉眼压计连续测量三次，彼此对对方的眼压测量结果不知情。计算受试者内标准差（Sw）、变异系数（CVw）（100×Sw/总体均值）和组内相关系数（ICC）以评估观察者内重复性。通过使用Bland-Altman描述的95%一致性界限和配对样本t检验分析观察者间差异。此外，对另外13只正常F344大鼠腹腔注射氯胺酮/赛拉嗪或水合氯醛，由一名操作人员每隔五分钟测量一次双眼眼压，直至动物苏醒。使用单因素方差分析比较不同时间点的眼压。
平均眼压为35.58mmHg（范围为17.33至65.33mmHg）。对于观察者内重复性，两名观察者高眼压的Sw分别为5.20mmHg/3.41mmHg，CVw分别为9.98%/8.08%，ICC分别为0.820/0.928。观察者间差异为两名观察者平均眼压的14.76%±19.76%，95%一致性界限为-23.97%至53.50%，这两名观察者的平均眼压差异具有统计学意义（P = 0.001）。麻醉后前15分钟眼压略有下降，眼压变化在0.17至1.17mmHg之间。眼压从麻醉前基线的11.75±2.05mmHg（n = 12）降至麻醉后20分钟的8.75±1.06mmHg（P = 0.001），这种低血压状态持续至麻醉后80分钟。
在该高血压大鼠样本中，托诺拉眼压计测量显示出较高的观察者内重复性，然而，其观察者间再现性较差。托诺拉眼压计可灵敏地检测出全身麻醉引起的眼压纵向变化。因此，我们建议使用托诺拉眼压计测量眼压最好由一名观察者进行，并且它可用于实验性青光眼研究。
