Abstract
Abstract: :
Purpose:To determine the IOP in genetically distinct mouse strains and to establish baseline data for use in aging and/or glaucoma research. Methods: Four different commonly used mouse strains, BALB/C, CBA/CAHN, AKR/J, and CBA/J, were selected because IOPs determined by canulation have been reported to be low, high, and intermediate (for the last two) respectively (Simon WM John, BMC Genetics 2001). Eyes from 12 animals, 6 male and 6 female, of each strain were measured at 8–10 wks of age. IOP measurements were performed in non–sedated but restrained mice under topical anesthesia using the rebound tonometer. IOPs were measured in all animals, on 2 different days during between 10AM & 12PM. Subsequently, a number of eyes from each strain were canulated to provide a calibration curve specific for that strain. Tonometer readings for all strains were converted to IOP values using the calibration data obtained from the respective strain. For comparison purposes IOP values were also obtained using the C57/BL6 calibration data previously reported. IOP for the four strains and between male and female animals within each strain were compared using ANOVA. Results: Using the specific calibration curve obtained for eyes of each strain, relative IOP (mean ± SEM) measured by the rebound tonometer was 6.15 (±0.22) mmHg (range 3 – 10 mmHg) for the BALB/C strain, 14.45 (±0.23) mmHg (range 8 – 24 mmHg) for the CBA/CAHN strain, 9.75 (±0.22) mmHg (range 6 –14 mmHg) for the AKR/J strain and 9.56 (±0.22) mmHg (range 5 – 21 mmHg) for the CBA/J strain. There was no statistically significant difference in IOP between genders for any of the strains (p>0.49, ANOVA). Using the C57 calibration curve, relative IOPs (mean ± SEM) were significantly lower for all strains, with small differences between them. The calibration curves obtained after canulation of eyes from each strain were statistically different (p< 0.001, ANOVA). Conclusions: Non–invasive IOP measurements confirm that the BALB/C strain has lower and the CBA/CAHN has higher IOPs than other mouse strains while the AKR/J and the CBA/J strains have intermediate IOPs. No gender differences in IOP were detected for any of the strains. The significant difference in the calibration curves between different strains indicates different corneal properties (corneal thickness, rigidity) and /or eye characteristics of genetically specific strains, and reinforces the need for individual strain calibration curves.
Keywords: intraocular pressure