Intraocular tissue plasminogen activator in a rabbit model of traumatic hyphema.

Tissue plasminogen activator was used to evaluate the clearance of traumatic hyphema in a rabbit model. A neodymium-YAG laser was used to disrupt iris vessels, creating a traumatic hyphema. Tissue plasminogen activator (1800 IU/0.1 mL) was injected into the anterior chamber 24 hours after creation of the hyphema. Two control groups (one receiving balanced salt solution and one receiving no treatment) were used for comparison. A multivariate analysis of covariance indicated that the greatest difference in hyphema clearance between the groups occurred at days 3, 4, and 5. Five days after tissue plasminogen activator treatment, the mean size of the clot remaining in the anterior chamber was 27% of that of the original hyphema. In control eyes, almost 60% of the original clot remained at day 5. Treatment of animals with tissue plasminogen activator doses of 5000 IU and 10,000 IU produced a substantial increase in repeated bleeding episodes in our rabbit model. We concluded that although the use of tissue plasminogen activator in our rabbit model of traumatic hyphema significantly improved clearance of blood from the anterior chamber, the remaining clot was of such size that the clinical benefit was questionable.