| Objective: To investigate the effect of modified Zhujing pill combined with posterior extrascleral injection of Tenon’s subcapsular myopia(AL),posterior scleral thickness and biomechanics on experimental form-deprivatedmyopia(FDM)in rabbits.Methods: 1.We selected 2-month-old Japanese big ear white rabbits,each weighing between 1 and 1.5kg,male and female,and randomly divided 60 rabbits into 5 groups with 12 rabbits in each group.They were Blank group(Group A),Model group(Group B),Drug group(Group C),Genipin cross-linked gelatin group(Group D)and genipin cross-linked gelatin combined with Combination group(Group E).2.Rabbits in group A were given no treatment.Group B left eyelid suture.Group C was given traditional Chinese medicine and eyelid suture.In group D,Tenon’s was injected subcapsular with Genipine crosslinking gelatin and eyelid suture.Group E received traditional Chinese medicine intragastric injection combined with Tenon’s subcapsular injection of Genipine crosslinking gelatin and eyelid suture.3.AL was measured by ultrasound.The drug distribution in the posterior sclera was observed by B-scan and CT.The orbital profile was used to observe the distribution of the drug in the orbit and the ocular wall.4.After the rabbits were anesthetized,both eyes were quickly removed.The scleral extrascleral tissue was removed and a 25mm×3 mm scleral strip specimen was made.The choroid and retina on the strip were stripped.A vernier card was then used to measure the posterior scleral band thickness.At this point,we can successively put the made bands into eyeball preservation solution 1,2,and 3.They were soaked separately for 10 minutes.Finally,they were stored in liquid nitrogen in preservation solution 4.5.We set out to test the biomechanics of the posterior sclera at room temperature.First,the frozen strips were quickly rewarmed in a 37 ℃ water bath.After the strip was well rewarmed,we fixed it to the Instron5943 tester and began testing.And record the generated data.Results:1.AL measurement results: Before the experiment,there was no significant difference in AL between groups(P>0.05),so the influence of rabbit congenital myopia on the experimental results can be excluded.The AL length of the experimental eye in group B was 0.65±0.72 mm compared with that in group A at 60 days after surgery,the difference was statistically significant(P<0.001),and the myopia modeling of FDM was successful.There was no significant difference in AL between group C and group B(P>0.05).The AL of the eyes in group D and E was respectively 0.42±0.47 mm and 0.56±0.70 mm shorter than that in group B and the difference was statistically significant(P<0.05).There was no significant difference in AL between the contralateral eyes of each group(P>0.05).2.Results of eye B-ultrasound examination: No abnormal echoes were observed in the vitreous.The echo of retina was regular.Crescent-like hyperechoic areas were observed in the posterior sclera of left eyes in groups D and E.The echo of the optic nerve was regular.No abnormal echoes were observed in the orbit.3.Results of orbital CT examination: A regular annular shadow of increased density was observed in the sclera behind the left eye in both groups D and E.The density is uniform,between scleral density and orbital bone density.The gap with the surrounding orbit was clear.4.Eyeball profile morphological observation results: The position of the genipin gelatin crosslinker to the posterior sclera is shown in dark blue.It adheres to and is integrated with the posterior sclera.The posterior pole had slightly more drug distribution than the periphery.The gap with surrounding tissue was clear.5.Measurement of posterior scleral band thickness 60 days after surgery: There was no significant difference in the posterior scleral band thickness between the eyes of rabbits in group A(P>0.05).The posterior scleral band of group B was 0.06±0.07 mm thinner than that of group A.The difference was statistically significant(P<0.01).There was no statistically significant difference in the thickness of posterior scleral bands between group C and group B(P>0.05).Compared with group B,the posterior scleral bands of group D and group E were thickened by 0.16±0.05 mm and0.21±0.07 mm,respectively,with statistically significant difference(P<0.001).There was no significant difference in the thickness of scleral strip in contralateral posterior eye among all groups(P>0.05).6.Biomechanical test results: There were no significant differences in scleral creep rate,ultimate stress,ultimate strain and elastic modulus in group A 60 days after surgery(P>0.05).The scleral creep rate of group B and group A respectively increased by 7.69±0.67% and 7.76±0.25%,and the ultimate strain respectively increased by 171.16±117.77% and 161.58±50.10% with statistical significance(P<0.05).There were no significant differences in ultimate stress and elastic modulus(P>0.05).In group C,the scleral creep rate of posterior eye increased by 5.38±1.14%and the ultimate strain increased by 249.58±189.15%,with statistical significance(P<0.05).Compared with group B,the scleral creep rate decreased by 2.55±1.43%,the difference was statistically significant(P<0.001),but the ultimate strain was not statistically significant(P>0.05).There were no significant differences in ultimate stress and elastic modulus(P>0.05).The scleral creep rate in group D and group B decreased by 2.45±0.97% and 10.27±0.47%,the ultimate stress increased by0.79±0.29 MPa and 0.84±0.28 MPa,and the elastic modulus respectively increased by8.14±5.50 MPa and 10.98±4.51 MPa.The difference was statistically significant(P<0.001).There was no significant difference in posterior scleral limit strain between experimental eyes and contralateral eyes in groups D and E(P>0.05),which decreased by 484.24±85.51% and 305.43±29.37% compared with experimental eyes in group B(P<0.001).The scleral creep rate of group E and group B decreased by4.30±0.83% and 12.26±0.63%,the ultimate stress increased by 0.93±0.44 MPa and0.94±0.38 MPa,and the elastic modulus respectively increased by 9.29±7.96 MPa and11.80±6.45 MPa.The difference was statistically significant(P<0.01).The displacement loading curve shows that group B is the most prone to deformation,and group E has the strongest resistance to deformation.Conclusion: Modified Zhujing pill combined with Tenon’s subcapsular postscleral injection of Genipine crosslinking gelatin can thicken rabbit posterior sclera and increase its biomechanical properties.The ultimate stress and elastic modulus increased.The ultimate strain and creep rate decrease.The posterior sclera has increased resistance to deformation and decreased elongation.It can effectively inhibit AL prolongation.The formation and progression of experimental FDM myopia in rabbits were successfully prevented. |
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