| Objective: The normal growth of sclera plays an important role in the process of ocular visualization and the process of high myopia.The aim of this study was to investigate the changes in the collagen expression and elastic modulus in scleral tissues of experimental high myopia,further explaining the mechanism of high myopia.Methods: 1-month-old New Zealand white rabbits were monocularly treated by eyelid suturation randomly to build experimental high myopia eye model,the eyes that not operated on were the normal control.After 60 days,the eye axis measurement was used to show the success of experimental high myopia eye model.The eyeballs were obtained to assess three regions of the sclera—anterior,equatorial and posterior.The three regions of the scleral tissues were then separately divided into four groups.The first group was made into scleral strips for elastic modulus measurement using an Instron 5544.The second group was HE stained for observation of the scleral structures.The third group was used for electron microscopy to observe the size distribution of collagen fibrils.The last group was homogenized and the concentration of hydroxyproline was measured to determine the collagen content.Results:(1)With the increase of months of age,the sclera tissue elastic modulus increasing(P<0.05),the collagen content increasing(P<0.05),and diameters of the collagen fibrils of each scleral region increasing(P<0.05).(2)HE staining showed a large number of fibroblasts distributed in various tissues,the number of sclera fibroblasts in various parts of the scleral tissue decreased and fiber bundles increased and became thicker with increasing age;High myopia group compared with 3months of fiber cells,fiber bundle is fine.(3)Transmission electron microscope toobserve collagen fibrils of different months sclera organization,sclera tissue collagen fibril diameter size heterogeneity,the diameter and quantity of the collagen fibrils changed with the increase of months,and there are differences between different areas,the posterior scleral collagen fibril average diameter less than the front of the sclera and equatorial ministry sclera.(4)To establish high myopia animal model through eyelid suture,axial relative extension.The posterior sclera of high myopia had a lower elastic modulus than the normal eyes elastic modulus(P<0.05).However,there was no significant difference as for the anterior and equatorial sclera(P>0.05).(5)The posterior sclera of high myopia had less hydroxyproline concentration than the normal eyes hydroxyproline concentration(P<0.05).However,there was no significant difference as for the anterior and equatorial sclera(P<0.05).Myopia group,the collagen fibril average diameter of the anterior and equatorial scleral was no obvious difference in the normal group,and then the posterior sclera collagen fibril average diameter smaller than in the normal group.Conclusion:(1)In the normal growth process,the biomechanical properties of the sclera,tissue structure,collagen fibril diameter and collagen content of the various parts continue to change,and there are differences between different parts of the sclera.(2)The elastic modulus and collagen content of sclera are increased with the increase of months,and the number of scleral fibroblasts in all parts of the scleral tissue are reduced with the increase of months.Sclera tissue collagen fibril average diameter increased with the increase of months,sclera tissue collagen fibril diameter size heterogeneity,and there are differences between different areas.(3)In the process of high myopia,posterior sclera occurs remodeling,collagen fibril average diameter and collagen content reduce,which was easy to expansion and deformation and thus lead to high myopia.However,there was no significant difference as for the anterior and equatorial sclera.(4)The experimental results can explain the mechanism of ocular visualization and high myopia in further,and provide theoretical guidance for high myopia prevention by treating the collagen. |
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