Intraocular pressure in inbred mouse strains

Purpose. To develop a protocol to measure the intraocular pressure (IOP) of living mice and to determine the IOP of genetically different mouse strains. Methods. Eyes of anesthetized animals were cannulated with a very fine fluid-filled glass microneedle. The microneedle was connected to a pressure transducer, and the pressure signal was analyzed with a computer system. Intraocular pressures of male C3H/HeJ, C57BL/6J, A/J, and BALB/cJ mice were determined. Results. Differences in IOP were detected between genetically distinct mouse strains maintained in virtually identical environments. C3H/HeJ was the strain with the highest average IOP (13.7 +/- 0.8 mm Hg). This strain average was 1.4 mm Hg higher than that for C57BL/6J (12.3 +/- 0.5 mm Hg; P = 0.14), 4.3 mm Hg higher than that for A/J (9.4 +/- 0.5 mm Hg; P < 0.001), and 6 mm Hg higher than that for BALB/cJ (7.7 +/- 0.5 mm Hg; P < 0.001). Conclusions. The authors have developed an accurate and reliable procedure for measuring intraocular pressure in living mice. This procedure can detect IOP differences between groups of mice that differ by genotype.