ABSTRACT
· AIM: To investigate the efficacy and safety of intravitreal injection of plasmin, hyaluronidase, or the combination of the two in inducing posterior vitreous detachment (PVD).· METHODS: 15 mini-type pigs were assigned to three groups (Group A, B and C), 5 in each group. One eye of each pig was intravitreally injected with the studying agent,and the fellow eye was used as control. Group A received a vitreous injection of hyaluronidase 50U (0.1mL); group B received plasmin 0.5U (0.1mL); group C received plasmin 0.5U (0.05mL) combined with hyaluronidase 50U (0.05mL). The fellow eyes in each group were injected with 0.1mL balanced salt solution (BSS). All the pigs were examined with slit-lamp biomicroscope, direct and indirect ophthalmoscope, B-scan and electroretinograph (ERG). After 7 days, the animals were killed and the eyes were enucleated and examined with light microscope, transmission electron microscope and scanning electron microscope.· RESULTS: B-scan examination showed that one eye of Group A and two eyes of Group B had partial PVD at 1st day after injection and one eye of Group C at 1 hour after injection. On the 7th day, B-scan, light microscopy and scanning electron microscopy demonstrated that all the eyes of Group A and Group B had partial PVD, while none of the control eyes had PVD. Rank sum test for scanning electron microscopy results of all the groups showed P ＜0.005.Furthermore, the comparisons between every two groups were made. The results of analyses were as follows: P＞0.05 between the drug injected eyes of Group A and Group B, P＜0.05 between Group B and Group C, Group A and Group C.The b-wave and a-wave amplitudes of ERG showed no significant difference either between preinjection and postinjection in all groups or between the drug injected eyes and the control eyes in each group. Light microscopy and transmission electron microscopy revealed no damage to the retinal structure.· CONCLUSION: Intravitreal injection of hyaluronidase 50U or plasmin 0.5U or their combination can produce PVD effectively and quickly without retinal functional or structural toxicity. The combination of the two proteases was proved to be synergetic.
ABSTRACT
We have developed a training system for endophthalmic surgery at Osaka Medical College and reviewed its effects on residents. The training program consists of preoperative and postoperative examinations, lectures on techniques such as suturing through microscopes, and exercises with pig eyes. Residents can practice any time with microsurgery instruments in our department. Such practice enables residents to acquire skills more easily. Highly sensitive microphones are attached to operative microscopes so that residents can learn during surgery and watch videotapes with faculty members afterward. Exercises with pig eyes are especially useful for practicing microsurgery. After basic training, residents start performing actual surgeries step by step under the supervision of faculty members until they master the basic techniques. We think highly of our educational method. Teaching hospitals should establish efficient systems for training in cataract surgery without negatively affecting patients.