Related Experiment Videos
The effect of prostaglandin F2 alpha on trabecular outflow facility in cynomolgus monkeys
1Department of Ophthalmology, University of Wisconsin Medical School, Madison 53792.
Abstract:
Cynomolgus monkeys were treated topically in one eye with 2 micrograms of prostaglandin F2 alpha -l-isopropylester (PGF2 alpha-IE) twice daily. On day 4, 3 hr after the seventh dose, intraocular pressure (IOP) was 8.1 +/- 0.7 mmHg lower in the treated than in the control eyes. On day 5, after the ninth PGF2 alpha dose, gross facility was measured in both eyes by determining the rate of fluid flow from an external reservoir into the eye at two different IOP levels. Simultaneously, trabecular facility was measured by determining the rate of accumulation of intracamerally infused radioiodinated albumin in the general circulation. Gross facility was 40-60% higher in PGF2 alpha treated than in control eyes, but there was no difference in trabecular facility. The increase in gross facility sometimes reported following PGF2 alpha probably represents increased pseudofacility or uveoscleral facility, rather than true facility of outflow through the trabecular meshwork and Schlemm's canal.
Insights
Prostaglandin F2 alpha-IE eye drops lowered intraocular pressure in monkeys. The drug increased overall fluid outflow (gross facility) but not through the primary drainage system (trabecular facility).
Area of Science:
- Ophthalmology
- Pharmacology
- Physiology
Background:
- Glaucoma treatment often aims to reduce intraocular pressure (IOP).
- Prostaglandin analogs are commonly used to lower IOP.
- Understanding the mechanism of action for IOP-lowering drugs is crucial.
Purpose of the Study:
- To investigate the effect of prostaglandin F2 alpha-isopropylester (PGF2 alpha-IE) on intraocular pressure and aqueous humor outflow in cynomolgus monkeys.
- To differentiate between changes in trabecular facility and other outflow pathways.
Main Methods:
- Cynomolgus monkeys received topical PGF2 alpha-IE in one eye twice daily.
- Intraocular pressure (IOP) was measured.
- Gross and trabecular facility were assessed using fluid flow and radioiodinated albumin measurements.
Main Results:
- Topical PGF2 alpha-IE significantly reduced IOP in treated eyes.
- Gross facility increased by 40-60% in PGF2 alpha-IE treated eyes compared to controls.
- No significant difference in trabecular facility was observed between treated and control eyes.
Conclusions:
- PGF2 alpha-IE effectively lowers intraocular pressure in non-human primates.
- The observed increase in gross facility is likely due to enhanced uveoscleral or pseudofacility, not increased trabecular outflow.
- This suggests prostaglandin analogs may lower IOP through mechanisms independent of the trabecular meshwork.