Purpose:
A retrospective study was carried out to determine the effect of age on aqueous humor dynamics in normotensive monkey eyes.
Methods:
Based on the monkey life cycle, nomotensive female cynomolgus monkeys were categorized as young age 3-5 yrs, middle age 6-10 yrs, and older age 11-15 yrs. Intraocular pressure (IOP) and outflow facility (C) were measured by an electronic indentation tonograph in a total of 33 monkeys. Aqueous humor flow rates (F) were measured by a scanning computerized fluorophotometer in 25 monkeys. Multiple measurements of IOP, C and F were performed in most monkeys at different ages. IOP and C were measured in 15 monkeys at 2 age categories, and 4 monkeys at 3 age categories. 7 monkeys had F measured at 2 age categories. For each monkey, the average of right and left eyes was used for statistical analysis.
Results:
The results are shown in Table 1. A reduction (p<0.001) of C was found comparing young, middle and old age groups. IOP was higher (p<0.05) in old age group than in young or middle age group. F was not (p>0.20) different among 3 age groups.
Conclusions:
In the normotensive aging monkey eye, IOP increases, tonographic outflow facility decreases and aqueous humor flow rates are unchanged. It remains to be determined if this age-associated reduction in outflow facility affects the assessment of ocular hypotensive agents.
Keywords: intraocular pressure • aging • aqueous