Intraocular drug penetration is dependent upon the physical and chemical characteristics of the drug, the manner of drug administration and the drug's ability to pass through the blood/aqueous barrier. Most systemically administered drugs do not achieve intraocular therapeutic levels. The authors present a new method to increase the intraocular concentration of intravenously administered drugs based on the premise that ocular hypotony by ocular compression produces a temporary break in the blood/aqueous barrier during the period of hypersecretion that follows to regain normal intraocular pressure levels. Vancomycin introduced parenterally was used as the drug model. The right eye of 22 rabbits served as experimental eye, while the left eye served as control. The concentrations of vancomycin in the aqueous humor half an hour after intravenous injection of 40 mg/kg vancomycin in 50 ml of lactated Ringer's solution were as follows: 30.17 +/- 20.68 micrograms/ml in the right (hypotonized) eyes and 4.92 +/- 3.33 micrograms/ml in the left (control) eyes. The difference in drug levels between the two sets of eyes had a high statistical significance at p = 0.001.