Plasmin and dispase in inducing posterior vitreous detachment in rabbit eyes

AIM:To evaluate the safety and efficacy of dispase and plasmin inducing posterior vitreous detachment(PVD)by intravitreal injection in rabbit eyes.METHODS:Forty-eight pigmented rabbits were ran- domized into 6 groups.Groups 1 and 5 received dispase 0.025 U in each of testing eye;group 2,dispase 0.1 U; groups 3 and 6,plasmin 1 U;group 4,plasmin 4 U.All groups received PBS in control eyes.Groups 5 and 6 were enthanized 15 minutes postoperatively for ocular histological examination.The remaining groups received clinical inspection,indirect ophthalmoscope,biomicroscopy,electroretinogram(ERG),together with scanning and transmission electron microscopy seven days postoperatively.RESULTS:Scanning electron microscopy re- vealed partial or complete PVD in the eyes which received dispase and plasmin in groupl,2,4(8/8,8/8,8/8), except group 3(6/8).Light microscopy showed inflammation changes in both dispase and plasmin treated eyes of group 5 and 6(8/8,8/8).However,ERG showed no significant change of dark adaptation eye a and b(P＞0.05) in plasmin treated eyes(group 3,4),and a significant reduction from baseline(P＜0.01)in dispase treated eyes (group 1,2).The ultrastructure damage of retina were found by transmission electron microscopy.Cell damage, retinal hemorrhage,and cataract formation were observed in eyes of group 1 and 2.No changes were observed in plas- min treated and the control eyes.CONCLUSION:Intravitreal injection of plasmin and dispase could induce PVD, but with lesser toxicity in case of the former than that of the latter.