Changes in scleral collagen organization in murine chronic experimental glaucoma.

PURPOSE

The organization of scleral collagen helps to determine the eye's biomechanical response to intraocular pressure (IOP), and may therefore be important in glaucoma. This study provides a quantitative assessment of changes in scleral collagen fibril organization in bead-induced murine experimental glaucoma.

METHODS

Wide-angle X-ray scattering was used to study the effect of bead-induced glaucoma on posterior scleral collagen organization in one eye of 12 CD1 mice, with untreated fellow eyes serving as controls. Three collagen parameters were measured: the local preferred fibril directions, the degree of collagen anisotropy, and the total fibrillar collagen content.

RESULTS

The mouse sclera featured a largely circumferential orientation of fibrillar collagen with respect to the optic nerve head canal. Localized alteration to fibril orientations was evident in the inferior peripapillary sclera of bead-treated eyes. Collagen anisotropy was significantly (P<0.05) reduced in bead-treated eyes in the superior peripapillary (Treated: 43±8%;

CONTROL

49±6%) and midposterior (Treated: 39±4%;

CONTROL

43±4%) sclera, and in the peripapillary region overall (Treated: 43±6%;

CONTROL

47±3%). No significant differences in total collagen content were found between groups.

CONCLUSIONS

Spatial changes in collagen fibril anisotropy occur in the posterior sclera of mice with bead-induced chronic IOP elevation and axonal damage. These results support the idea that dynamic changes in scleral form and structure play a role in the development of experimental glaucoma in mice, and potentially in human glaucoma.