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Structural and ultrastructural changes to the sclera in a mammalian model of high myopia

Version 2 2024-06-03, 18:45
Version 1 2017-07-17, 14:36
journal contribution
posted on 2024-06-03, 18:45 authored by NA McBrien, LM Cornell, Alex GentleAlex Gentle
PURPOSE: The development of high myopia is associated with scleral thinning and changes in the diameter of scleral collagen fibrils in humans. In the present study, the association between these scleral changes and the losses in scleral tissue that have previously been reported in animal models were investigated to determine the relationship between changes in collagen fibril architecture and thinning of the sclera in high myopia. METHODS: Myopia was induced in young tree shrews by monocular deprivation of pattern vision for short-term (12 days) or long-term (3-20 months) periods. Scleral tissue from normal animals over a wide age range (birth to 21 months) was also collected to provide data on the normal development of the sclera. Light and electron microscopy were used to measure scleral thickness and to determine the frequency distribution of collagen fibril diameters in the sclera. Tissue loss was monitored through measures of scleral dry weight. RESULTS: Significant scleral thinning and tissue loss, particularly at the posterior pole of the eye, were associated with ocular enlargement and myopia development after both short- and long-term treatments. However, collagen fibril diameter distribution was not significantly altered after short-term myopia treatment, whereas, from 3 months of monocular deprivation onward, significant reductions in the median collagen fibril diameter were noted, particularly at the posterior pole. CONCLUSIONS: The results of this study demonstrated that loss of scleral tissue and subsequent scleral thinning occurred rapidly during development of axial myopia. However, this initial tissue loss progressed in a way that did not result in significant alterations to the collagen fibril diameter distribution. In the longer term, there was an increased number of small diameter collagen fibrils in the sclera of highly myopic eyes, which is consistent with findings in humans and is likely to contribute to the weakened biomechanical properties of the sclera that have previously been reported.

History

Journal

Investigative ophthalmology & visual science

Volume

42

Pagination

2179-2187

Location

Rockville, Md.

ISSN

0146-0404

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

2001, Association for Research in Vision and Ophthalmology

Issue

10

Publisher

Association for Research in Vision and Ophthalmology

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