Noninvasive measurement of rodent intraocular pressure with a rebound tonometer.
OBJECTIVE
The present study evaluated the applicability of a rebound tonometer in measuring intraocular pressure (IOP) in rats and mice.


METHODS
The accuracy of the TonoLab rebound tonometer was determined in cannulated mouse and rat eyes. IOP was manipulated by changing reservoir height, and tonometer pressure readings were recorded by an independent observer. IOP values were recorded in conscious Wistar rats and in four different strains of mice. The effects of anesthesia on IOP were evaluated in two different strains of mice.


RESULTS
The IOP readings generated by the rebound tonometer correlated very well with the actual pressure in the eye. In rats, this linear correlation had a slope of 0.96 +/- 0.05 (mean +/- SEM, n = 4) and a Y-intercept of -2.1 +/- 1.2. In mice, the slope was 0.99 +/- 0.05 (n = 3), and the Y-intercept was 0.8 +/- 1.4. Using this method, the resting IOP of conscious male Wistar rats was observed to be 18.4 +/- 0.1 mm Hg (n = 132). In mice, strain differences in IOP were detected. Baseline IOP values in Balb/c, C57-BL/6, CBA, and 11- to 12-month-old DBA/2J mice were 10.6 +/- 0.6, 13.3 +/- 0.3, 16.4 +/- 0.3, and 19.3 +/- 0.4 mm Hg (n = 12), respectively. In separated studies, anesthesia lowered IOP from 14.3 +/- 0.9 to 9.2 +/- 0.5 mm Hg (n = 8) in C57-BL/6 mice, and from 16.6 +/- 0.4 to 9.4 +/- 0.6 mm Hg (n = 10) in CBA mice.


CONCLUSIONS
The rebound tonometer was easy to use and accurately measured IOP in rats and mice. This technique, together with advances in genetic and other biological studies in rodents, will be valuable in the further understanding of the etiology and pathology of glaucoma.
Wang
Wan-Heng
WH
Alcon Research, Ltd., Fort Worth, Texas 76134, USA.
Millar
J Cameron
JC
Pang
Iok-Hou
IH
Wax
Martin B
MB
Clark
Abbot F
AF
D000772:Anesthesia, Local; D000779:Anesthetics, Local / Q000008:administration & dosage; D000818:Animals; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008811:Mice, Inbred DBA; D051381:Rats; D017208:Rats, Wistar; D015203:Reproducibility of Results; D014065:Tonometry, Ocular / Q000295:instrumentation / Q000379:methods*
D000779:Anesthetics, Local