Allogeneic Sclera Ball After Implantation Experiments On Guinea Pig Sclera And Refractive Effects

PartⅠThe structures of extraocular muscles of guinea pigPurpose:To locate the structures ofextraocular muscles of guinea pig.Methods:The location of the extraocular muscles was investigated and photographed magnification under the zeiss dissection microscope in 10 healthy 10-week guinea pigs.Results:Four rectus muscles(superior rectus,inferior rectus,two medial rectus muscles),two oblique muscles(superior obliquus,inferior obliquus)and retractor bulbi muscle were found.The guinea pig was lack of lateral rectus.Conclusions:Compared with human temporal anatomy,the extraocular muscles of guinea pig there are some exceptions.PartⅡThe application comparison between streak retinoscopy and eccentric infrared photoretinoscopy in the eyes of guinea pigsPurpose:This study investigated the results measured by streak retinoscopy(SR)and eccentric infrared photoretinoscopy(EIP)and the effect of cyclopentolate cycloplegic on the refraction measurement in juvenile guinea pigs.Methods:13 animals(3 weeks)were randomly examined thrice by SR and EIP both pre and post myddasis.The measuring time points of SR was at 9:00,10:00,11:00, 14:00,15:00,16:00 and by EIP at 9:30,10:00,11:30,14:30,15:30 and 16:30 in the measuring day.1%cyclopentolate hydrochloride was topically administrated to the eye every five minutes for three times from the time of 13:00.Results:The average refraction of SR in pre-mydriasis and post-mydriasis were 3.03±0.65D(Mean±S.E.)and 3.30±0.67D respectively,the average correlate coefficients of three values were 0.979 in pre-mydriasis and 0.980 in post-mydriasis. The average refraction of EIP in pre-mydriasis and post-mydriasis were 3.25±1.03D and 3.98±0.97D respectively,the average correlate coefficients of three values were 0.931 in pre-mydriasis and 0.962 in post-mydriasis.The correlation coefficients of the average refractions between SR and EIP was 0.851(p=0.000)in pre-mydriasis and 0.791 in post-mydriasis(p=0.000).The average refraction measured by two methods both showed significant difference between them in pre and post mydriasis(paired sample t-test),and they showed significantly correlation between them in pre and them in post mydriasis(bivariate correlations)(SR:t=2.945,p=0.046;r=0.982,p =0.000.EIP:t=3.494,p=0.002;r=0.980,p=0.000).The results indicated that mydriasis has not significantly affected the reliability of both two methods(repeated measures,SR:F=0.081,p=0.264;EIP:F=0.777,p=0.610).Conclusions:This study demonstrated that the refractive results of two methods were correlatively and both stable,however,the stability of the results measured by SR was better than that of EIP.The effect of cyclopentolate cycloplegic on juvenile guinea pigs in refraction is limited.The refraction of guinea pig can be measured by SR and EIP naturely without cyclopentolate cycloplegic administrated and the results are very stable.PartⅢThe histology study on the sclera strip in the posterior sclerai reinforcementPurpose:To investigate the tissue mechanism of the posterior scleral reinforcement and the result of the scleral strips in guinea pigs.Methods:24 animals were divided into 4 groups,A:curling scleral strip implantation group,B:sticking scleral strip implantation group,C:sticking scleral strip implantation with methylprednisolone sodium succinate injected group,D:sticking scleral strip implantation with methylprednisolone sodium succinate injected group. The scleral strips were come from the normal 10-week guinea pig.The animals of C group and D group were injected methylprednisolone sodium 4mg/0.1ml and succinate methylprednisolone sodium succinate 0.1ml respectively at 0,3,6 days postoperatively.The operative eyes were enucleated after the animals killed in the 9 and 51 days postoperatively,and the tissue was examined by light microscopy and electron microscope.Results:At 9 days postoperatively,there were inflammatory capsules around all scleral strips.The strips were most swelling and the cells were sparseness in the capsules of group A.The strips were least swelling and the capsules were thickest in all groups.The macrophages were actively in the tissues.In 51 days postoperatively, the strips were absorbed mostly in group A.The strips were closed with the host globes and infiltrated with lots of fibroblasts in group C.The other strips were partly absorbed in other two groups.There were fibroblasts secreting collagen infiltrated the graft strips.Conclusions:Obviously inflammation process was observed around the host globes after the implantation with homologous scleral strips.The implantation method and the degree of inflammation would affect the formation of capsules and the results of the strips.PartⅣThe refraction changes after the homologous sclera reinforcement in the eyes of guinea pigsPurpose:To evaluate and analyze the refraction changes after the homologous scleral implantation in guinea pigs.Methods:Experiment 1:the effect of the sclera on the refraction changes in guinea pigs.40 4-week guinea pigs were equally divided into 4 groups,A:normal control group,B:sham operation group,C:2mm wide scleral strip group,D:3mm wide scleral strip group.2mm wide and 3 mm wide scleral strips were implanted in C group and D group respectively.The cornea curvature,refraction,eye axis were measured at the preoperative,3 days,9 days,16 days,23 days,30 days,37 days,44 days,51 days postoperatively.Repeated measures were performed to analyze the results.Experiment 2:the expression of MMP-2 mRNA in the host sclera of guinea pigs after the post sclera reinforcement.Every group contains 4 guinea pigs at 6 days and 37 days postoperatively.RT-PCR and real-time PCR were used to measure the mRNA expression level of MMP-2.The results were analyzed by ANOVA.Experiment 3:the effect of methylprednisolone sodium succinate on the refraction changes of the guinea pigs with sclera reinforcement.50 4-week guinea pigs were equally divided into 5 groups,A:normal control group,B:normal+ methylprednisolone sodium succinate aqueous solution,C:3mm wide scleral strip group,D:3mm wide scleral strip+methylprednisolone sodium succinate aqueous solution group,E:3mm wide scleral strip+sterile water for injection.B group and D group were injected methylprednisolone sodium succinate aqueous solution,E group were injected sterile water in peri-bulb at the operation finished,3 days and 6 days postoperatively.The cornea curve,refraction,eye axis were measured at the preoperative,3 days,9 days,16 days,23 days,30 days,37 days,44 days,51 days postoperatively.Repeated measures were performed to analyze the tendency of refraction change.The index changes in the 9 days postoperatively were analyzed by ANOVA.Results:Experiment 1:There were a transiently process that the refraction was first drift to myopia and then recovery in the operation groups.The difference of different time points in vary groups were significant(F=14.477,P=0.000).The difference of refraction changes were significantly between normal control group and 3mm wide sclera strip(P=0.005),sham operation group and 3mm wide sclera strip(P=0.004). The tests of between-subjects effects showed that the difference of refraction(F= 4.302,P=0.012)and the depth of vitreous chamber(F=3.571,P=0.025)were statistical significance.It means that the group factors effected the tendencies of refraction change and vitreous chamber depth change.Exoeriment 2:The tests of within-subjects effects showed there was statistical significance of total variation of MMP-2 mRNA expression m the sclera ot operated eyes at 6 days post-operatively(F=3.591,P=0.012)and 37 days postoperatively(F =2.819,P=0.040).Comparing with the normal group at 6 days post-operatively,the MMP-2 mRNA expression of follow eyes of sham operated eye(P＜0.05)and operated eye(P＜0.01)elevated significantly.However,the MMP-2 mRNA expression of operative eyes were dropped significantly with the fellow eyes(P= 0.018).Comparing with the left eyes in normal eyes at 37 days post-operatively,the MMP-2 mRNA expression of follow eyes of sham operated eye(P=0.035)and operated eye(P=0.034)elevated significantly,and the MMP-2 mRNA expression of operative eyes were dropped significantly with the fellow eyes(P=0.011).Experiment 3:The myopia drift were partly controlled in 3mm wide scleral strip +methylprednisolone sodium succinate aqueous solution group.The tests of between-subjects effects showed the factors of group effected the refraction change with statistical significance(F=3.434,P=0.018).The refraction and eye axis changes during 9 days post-operatively analyzed by ANOVA.The results showed there were significant differences between D group and C group(P=0.008),D group and E group(P=0.013)in refraction changes.It was presented there was significant differences in the changes of eye axis between C group and A group(P=0.016),E group and A group(P=0.032),C group and B group(P=0.002),E group and B group(P=0.004).However,there was not significant difference in the changes of eye axis between the D group and A group,D group and B group.Conclusions:There were a transiently process that the refraction was first drift to myopia and then recovery in the homologous scleral implantation in guinea pigs.It maybe caused the rejection of host.The MMP-2 mRNA expression of were dropped in the sclera of the operated eyes and lifted in the fellow eyes.The myopia drift were partly controlled by methylprednisolone sodium succinate.It indicated that we shold pay high attention on the histocompatibility,stability of the graft and the degree of inflammation of the posterior sclera reinforcement.