Effects of intravitreal dispase on vitreoretinal interface in rabbits

To explore the efficacy and safety of dispase on the production of posterior vitreous detachment (PVD) following intravitreal injection at various concentrations for different exposure times in the rabbit eyes.

Sixty-four pigmented rabbits were assigned to two groups according to different combinations of concentrations of dispase and exposure times, namely group 1 (10, 5, or 1 U/ml for 30 min) and group 2 (0.25, 0.1, or 0.05 U/ml for one week). The control was established in both groups. One eye of each experimental rabbit was injected with dispase, and one eye of each control rabbit was injected with phosphate buffered saline. The presence of PVD and intraocular toxicity were observed by biomicroscope, macroexamination, and histology.

None of the control eyes showed PVD. In group 1, PVD was present in 6 of 7 eyes in each sub-group. In group 2, all 7 eyes of 0.25 U/ml or 0.1 U/ml and 6 of 7 eyes of 0.05 U/ml showed PVD. Intraocular toxicity including inflammation in anterior chamber, vitreous haze, epiretinal membrane, and retinal damage were found in the experimental eyes with relatively higher concentrations of dispase.

Although dispase has a definite effect on the induction of PVD in rabbits, its toxicity to retina also alerts us to the application in clinic. The intravitreal injection of dispase of 1 U/ml for 30 min may be acceptable.