Optical coherence tomography microscopy image measurements revealed that central corneal thickness was significantly reduced in
Fbn1+/− mice compared to WT. Radius of curvature also was significantly different between the two groups, although there was no significant correlation between the two variables, which may be a symptom of underpowering the study. A significant reduction in central corneal thickness has been reported in human patients with MFS.
31–33 A significant difference in keratometry readings also has been reported, suggesting a flattened cornea in MFS.
31,33–35 Increased radius of curvature and increase in axial globe length in MFS cornea has been observed in previous studies.
34,36 Therefore, based on these previous studies, and results obtained in the current study, we contend that the elastic fiber system has an important role in maintaining the curvature of the cornea. A reduction/malformation of taut elastic fibers in MFS would result in the cornea being pulled outwards at the periphery by an expanding globe following a release in internal stress, leading to a thin and flattened cornea. Elastin and elastin-free microfibril bundles are located in the sclera.
6,37 This would imply an alteration in biomechanical properties in the sclera, as well as in the cornea, in MFS patients' eyes. With one of the main functions of the sclera being to maintain fixed axial dimensions to ensure a stable retinal image,
38 and with absolute quantities of elastic tissue in the sclera unknown, it is likely that increased globe dimensions and subsequent flattened cornea associated with MFS are caused by a combination of biomechanical changes in the cornea and sclera. However, differences in corneal curvature in MFS patients, with no significant difference in axial length has been reported,
39 which demonstrates the phenotypic variability of the disease. With no correlation between radius of curvature and central corneal thickness between
Fbn1+/− and WT mice detected, it is unlikely that corneal stretching alone is responsible for the observed changes in thickness. The biomechanical behavior of MFS cornea recently has been assessed in vivo using an ocular response analyzer, revealing a greater maximal deformation of the MFS cornea compared to control, which in turn indicates decreased resistance to bending.
39 This evidence supports the proposal that elastic fibers have a pivotal role in providing the cornea with mechanical strength/elastic recoil, and maintaining corneal curvature.