AIM:To determine the effects of Latrunculin-B (Lat-B )on intraocular pressure (IOP),aqueous humor flow (AHF),uveoscleral outflow.METHODS:Topical Lat-B was administered to one eye,and vehicle to the other.IOP was measured by Goldmann tonometry.The IOP were measured at 1 hour before administration and 1 hour,2,3,4,5,6,24 hours after administration respectively;immunofluorescence was detected by instillation of FITC-BSA into anterior chamber,at 2,4,6,8,10 hours,2 rabbits were killed and frozen section of the eyes were done,and then the fluorescence intensity of ciliary body,epichoroidal space,anterior and posterior sclera were detected respectively.RESULTS:Lat-B could decrease the IOP,compared with the IOP before drug administration,the difference was significant(P<0.05),and this effect occurred within 1 hour,some IOP effect may remained for 24 hours,but the IOP of BSS group and DMSO group were not decreased.The fluorescence intensity of ciliary body,epichoroidal space,anterior and posterior sclera after drug administration of Lat-B were higher than that of BSS group and DMSO group(P<0.05),there was no difference between BSS group and DMSO group(P>0.05).CONCLUSION:Lat-B can decrease IOP and this effect occurred within 1 hour,remained effective at 24 hours;Lat-B may be used in the therapy of glaucoma by increasing the uveoscleral outflow facility,especially in NTG and POAG.