Effects of Growth and Development on Aqueous Humor Dynamics in Male Dutch Belted Rabbits.

PURPOSE

This study reports the changes in aqueous humor dynamics (AHD) and biometric parameters associated with growth and maturation in male Dutch-belted rabbits.

METHODS

In this prospective observational study, 20 male Dutch-belted rabbits were studied at 4-weekly intervals starting at 10 weeks through 38 weeks of age. Data collected included intraocular pressure (IOP), aqueous flow, outflow facility by tonography and fluorophotometry (acetazolamide method), episcleral venomanometry, central corneal thickness, corneal diameter, anterior chamber depth, and testicular volume. Uveoscleral outflow was calculated using the modified Goldmann equation.

RESULTS

Body mass plateaued by 26 weeks and testicular volume by 18 weeks. The anterior chamber depth plateaued by 18 weeks, whereas corneal thickness and diameter continued to increase throughout the study. IOP had peaks at 18 and 34 weeks and troughs at 26 and 38 weeks. Episcleral venous pressure increased until 22 weeks. Aqueous flow was relatively stable throughout the study. Uveoscleral outflow increased at approximately 26 weeks corresponding to the first IOP trough. Outflow facility peaked at 38 weeks corresponding to the second IOP trough. Acetazolamide failed to reduce IOP at weeks 10 to 18. Multivariate analysis showed all AHD variables from the Goldmann equation (except EVP in the 34-38-week period) to be significantly correlated with IOP changes in all periods.

CONCLUSIONS

An increase in IOP of up to sexual maturation may be due to a generalized increase in systemic vascular pressures. An increase in anterior chamber depth and uveoscleral outflow around the time of peak body mass at 26 weeks likely explains the IOP decrease at that time. An increase in outflow facility may be the last to peak with a resultant decrease in IOP.