Measurement of Intraocular Pressure (IOP) in the Mouse Eye Using an Impact Probe

Abstract

Abstract: : Purpose: To evaluate the applicability of rebound tonometry for measurement of IOP in the mouse eye. Methods: An induction/impact probe tonometer previously used for measurement of IOP in rats (Kontiola et al, Danias et al, Goldblum et al ARVO 2000, 2001) was modified to allow use on the smaller mouse eye. Motion parameters of the probe are related to the IOP and to mechanical and compliance properties of the cornea. Four eyes from adult C57 mice were cannulated ex vivo with a 26G needle and manometrically maintained at IOPs ranging from 5 to 60 cm H₂0 (3.6-44.1mmHg) using the open stopcock method. Five measurements per eye were obtained for each of ten IOP levels tested. IOP was correlated with the rate of deceleration of the impact probe and the ratio of speed at impact/deceleration. Correlation coefficients were calculated. Results:  

Statistical analysis showed an excellent correlation between IOP and mean deceleration (R₂=0.97 after logarithmic transformation) and mean velocity/deceleration (R₂=0.99 after second order polynomial transformation) measurements. Replicate measurements on the same eye (n=5) had standard errors of less than 6.7% of the mean. Conclusion: Rebound tonometry can be used to determine IOP in the mouse eye. This is a potentially useful technique for in-vivo non-invasive assessment of IOP in mouse eyes over a pressure range of 3.6 to 44mmHg.

Keywords: 444 intraocular pressure • 316 animal model