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in humans by the wearing of eyeglasses or contact lenses for myopia, prevents the recovery response.49,63 In contrast to the animals allowed to recover from induced myopia, animals wearing lenses that fully corrected the induced myopia did not recover and their sclerae retained a ‘myopic’ phenotype of reduced glycosaminoglycan synthesis (Fig. 13) and reduced thickness.49 This phenotype persisted over an extended period of lens wear and beyond the period during which eye growth was found to stabilize. Despite the fact the visual image is immediately placed in focus on the retina, and that the eye has returned to a stable growth rate, the sclera retains a myopic biochemical phenotype for a substantial period of time. Such a finding has important implications for the correction of human myopia.
Summary and Conclusions
This review chapter has interpretated the implications of current research findings in humans and in animal models to highlight the role of the sclera in myopia development and progression. In applying current knowledge of the development, structure, and function of the sclera, the ways in which the scleral ultrastructure, and the related biomechanical properties, are altered in myopia development and ultimately lead to the pathological changes seen in human high myopia have been highlighted. This review has provided an updated model of scleral thinning in highly myopic eyes. From the current research evidence, the feasibility of treatments for myopia-related scleral pathology to prevent the aberrant remodelling process in the sclera, thus preventing scleral tissue loss, thinning, and the long term development of a weakened scleral collagen fibril matrix are now an option to control or ameliorate the pathophysiology associated with high myopia.
Acknowledgments
The majority of the data presented in this review came from projects funded by the National Health and Medical Research Council of Australia and the Welcome Trust. I particularly acknowledge my research colleagues Alex Gentle, Andrew Jobling, and John Phillips who have made substantive contributions to data collected on scleral changes in myopia in our laboratory.
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