ABSTRACT
· AIM: To evaluate the safety of eye anterior tissue when plasmin (Pm) and hyaluronidase (HS) are injected into pigs'vitreouses to induce posterior vitreous detachment(PVD).· METHODS: 15 pigs without ocular diseases were randomly assigned to groups A,B,C (5 in each group). For each pig, one eye was experimental, the other eye was control. The experimental eye received intravitreal injection with enzyme:group A: 50U(0.1mL) HS; group B: 0.5U(0.1mL) Pm; group C: 0.5U(0.05mL) Pm combined with 50U(0.05mL) HS; while the control eye received intravitreal injection with equivalent dose of balanced salt solution (BSS). Postoperative reactions in the eyes were carefully observed by clinical examinations such as slit-lamp microscopy and direct and indirect ophthalmoscopy and measurement of intraocular pressure (IOP). Eyeballs were extirpated 7 days after the operation and histological examination was carried out. The corneas and irises were observed under light microscope (LM). The epithelia of ciliary bodies and lens were studied with transmission electron microscope (TEM).· RESULTS: In all experimental eyes and control eyes of group A, B and C, histological examination showed: under LM ,the corneas and irises of experimental eyes had no histological abnormality in structure; Under TEM, epithelial cells of ciliary bodies and the lens were tightly arrayed with clear cellular boundaries, clear intracellular structure, intact cell membranes, and intact nuclei; There was no significant difference in the clinical examinations and in the change of IOP between preoperation and postoperation, between the experimental group and the control group.· CONCLUSION: With 0.5U Pm and HS 50U injected into pigs' vitreouses to induce PVD, alone or combined with two enzymes, evaluation revealed no evidence of toxicity on the eye anterior tissue. The dosage was proved to be safe for eye anterior tissue.