title: Transverse depth-dependent changes in corneal collagen lamellar orientation and distribution.
abstract: It is thought that corneal surface topography may be stabilized by the angular orientation of out-of plane lamellae that insert into the anterior limiting membrane. In this study, micro-focus X-ray scattering data were used to obtain quantitative information about lamellar inclination (with respect to the corneal surface) and the X-ray scatter intensity throughout the depth of the cornea from the centre to the temporal limbus. The average collagen inclination remained predominantly parallel to the tissue surface at all depths. However, in the central cornea, the spread of inclination angles was greatest in the anterior-most stroma (reflecting the increased lamellar interweaving in this region), and decreased with tissue depth; in the peripheral cornea inclination angles showed less variation throughout the tissue thickness. Inclination angles in the deeper stroma were generally higher in the peripheral cornea, suggesting the presence of more interweaving in the posterior stroma away from the central cornea. An increase in collagen X-ray scatter was identified in a region extending from the sclera anteriorly until about 2 mm from the corneal centre. This could arise from the presence of larger diameter fibrils, probably of scleral origin, which are known to exist in this region. Incorporation of this quantitative information into finite-element models will further improve the accuracy with which they can predict the biomechanical response of the cornea to pathology and refractive procedures.
authors: Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff CF24 4HQ, UK.
authors: Ahmed
authors: A
authors: Abass
authors: Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff CF24 4HQ, UK.
authors: Sally
authors: S
authors: Hayes
authors: Visual Science Bioimaging Labs (VSBL), School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff CF24 4HQ, UK.
authors: Nick
authors: N
authors: White
authors: Diamond Light Source Ltd, Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK.
authors: Thomas
authors: T
authors: Sorensen
authors: Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff CF24 4HQ, UK meekkm@cardiff.ac.uk.
authors: Keith M
authors: KM
authors: Meek
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D003094:Collagen / Q000737:chemistry*; D003315:Cornea / Q000000981:diagnostic imaging* / Q000502:physiology*; D019781:Corneal Topography; D005260:Female; D006801:Humans; D008297:Male; D008567:Membranes, Artificial; D008875:Middle Aged; D011859:Radiography; D012542:Scattering, Radiation; D012590:Sclera / Q000473:pathology; D014961:X-Ray Diffraction; D014965:X-Rays
chemical_list: D008567:Membranes, Artificial; D003094:Collagen
keywords: X-ray scattering; collagen; collagen orientation; cornea; corneal biomechanics
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