Morphological changes of sclera in rats with experimental myopia.

Background. The absence of adequate experimental myopia model is the actual problem in pathophysiological studying of the myopia progression. Studies of the chick eye have formed the basis for several hypotheses of myopic development. The most pathogenesis reasonable myopia animal model is a form-deprivation myopia in chicks. It is necessary to study the dynamics of morphological changes in sclera in rats with form-deprivation myopia. Purpose. To investigate changes in the linear dimensions of eyeball and the morphological features of sclera in form-deprivation myopia in rats. Methods. In rats aged 14 days simulated form-deprivation myopia by blepharorrhaphy. The linear dimensions of the eyeball and morphological properties of sclera were studied on the 7th and 14th day of the experiment. Properties of sclera has been studied on the light and electron microscopic level. Results. The studies revealed increasing of sagittal, horizontal and vertical sizes of eyeball in rats with form-deprivation myopia. Sagittal size of the eye in intact rats aged 30 days was on average 4,84±0,08 mm, at the age of 90 days 5,14±0,01 mm. On the 14-th day of modeling myopia (age rats 30 days) sagittal size of the eye averaged 5,18±0,06 mm. The collagen fibrils architectonics changes in sclera were revealed mainly in the posterior pole of eyeball. Architectonics broken collagen fibers observed fragmentation, swelling, reduced cell number. Revealed deformation of the scleral ring in the optic disc. Conclusion. Vision deprivation in rats leads to increased growth rate of the linear dimensions of eyeball, more sagittal compared to intact animals (p<0,05), suggesting the development of axial myopia. Minimal changes of sclera collagen fibrils such as swelling were set in the equatorial region of myopic eyeball. Disorders of architectonics and structure of collagen fibrils, degenerative and destructive changes in fibroblasts, deformation of the scleral ring were revealed in the posterior pole of eye, which may be a sign of developing myopic scleral staphyloma.