Johnson Thomas V, Fan Shan, Toris Carol B
Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, NE 68198-5840, USA.
J Ocul Pharmacol Ther. 2008 Apr;24(2):175-85. doi: 10.1089/jop.2007.0114.
The aims of this study were to evaluate the accuracy, repeatability, and safety of multiple intraocular pressure (IOP) measurements by a commercially available rebound tonometer in conscious, conditioned mice, and to characterize the acute and profound effects of anesthesia on IOP in mice.
To test the accuracy of the tonometer, IOPs of CD-1 mice under ketamine/xylazine anesthesia were experimentally set and monitored with a water manometer/transducer system following transcorneal cannulation while simultaneously performing tonometry. The long- and short-term repeatability of the tonometer was tested in conscious, restrained mice, as measurements were taken once-daily in the afternoon for 4 consecutive days. On day 5, IOPs were measured in the same mice once every 4 min for 32 min. On 2 separate days, mice were administered ketamine/xylazine or 2,2,2-tribromoethanol anesthesia, in a crossover design, and IOPs were measured once every 2 min for 32 min. Rebound tonometry was performed in conscious mice before and 1 hour after 1 drop of timolol maleate (10 microL of 0.5%) application to 1 eye.
IOP measurements by rebound tonometry correlated well with manometry for pressures between 8 and 38 mmHg (y = 0.98x - 0.32, R(2) = 0.94; P < 0.001). The average tonometric IOP was invariant over 4 days (range, 11.7-13.2 mmHg). IOPs dropped significantly ( P < or = 0.05) within 6 min (ketamine/xylazine) or 10 min (2,2,2-tribromoethanol) postadministration of anesthesia but not with conscious restraint. Timolol significantly (P < 0.001) lowered IOP from 12.8 +/- 0.3 (mean +/- standard error of the mean) to 10.1 +/- 0.6 mmHg, as measured by the tonometer.
Rebound tonometry can be used to obtain accurate IOP measurements in conscious, restrained mice while avoiding the rapid and profound ocular hypotensive effects of general anesthesia. Small changes in IOP with an aqueous-flow suppressant are readily detectable with conscious restraint that may be missed with chemical restraint.
本研究旨在评估一种市售回弹式眼压计在清醒、适应环境的小鼠中多次测量眼压（IOP）的准确性、可重复性和安全性，并描述麻醉对小鼠眼压的急性和显著影响。
为测试眼压计的准确性，在氯胺酮/赛拉嗪麻醉下对CD-1小鼠的眼压进行实验设定，并在经角膜插管后用水压计/换能器系统进行监测，同时进行眼压测量。在清醒、受限的小鼠中测试眼压计的长期和短期可重复性，因为连续4天每天下午测量一次。在第5天，对同一只小鼠每隔4分钟测量一次眼压，共测量32分钟。在2个不同的日子里，采用交叉设计给小鼠注射氯胺酮/赛拉嗪或2,2,2-三溴乙醇麻醉，并每隔2分钟测量一次眼压，共测量32分钟。在给一只眼睛滴1滴马来酸噻吗洛尔（10微升0.5%）之前和之后1小时，对清醒小鼠进行回弹式眼压测量。
回弹式眼压测量法测得的眼压与压力计测量的眼压在8至38 mmHg之间具有良好的相关性（y = 0.98x - 0.32，R(2) = 0.94；P < 0.001）。眼压计测量的平均眼压在4天内保持不变（范围为11.7至13.2 mmHg）。麻醉后6分钟（氯胺酮/赛拉嗪）或10分钟（2,2,2-三溴乙醇）内眼压显著下降（P ≤ 0.05），但清醒受限状态下则无此现象。用眼压计测量，噻吗洛尔可使眼压从12.8 ± 0.3（平均值 ± 平均标准误差）显著降低至10.1 ± 0.6 mmHg（P < 0.001）。
回弹式眼压测量法可用于在清醒、受限的小鼠中获得准确的眼压测量值，同时避免全身麻醉引起的快速而显著的眼压降低效应。使用水流抑制剂时眼压的微小变化在清醒受限状态下易于检测到，而在化学约束下可能会被遗漏。
