Changes in collagen orientation and distribution in keratoconus corneas.
OBJECTIVE
To map the collagen orientation and relative distribution of collagen fibrillar mass in keratoconus corneal buttons.


METHODS
Structural analysis was performed by obtaining synchrotron x-ray scattering patterns across the samples at 0.25-mm intervals. The patterns were analyzed to produce two-dimensional maps of the orientation of the lamellae and of the distribution of total and preferentially aligned lamellae.


RESULTS
Compared with normal corneas, in keratoconus the gross organization of the stromal lamellae was dramatically changed, and the collagen fibrillar mass was unevenly distributed, particularly around the presumed apex of the cone.


CONCLUSIONS
The development of keratoconus involves a high degree of inter- and probably intralamellar displacement and slippage that leads to thinning of the central cornea and associated changes in corneal curvature. This slippage may be promoted by a loss of cohesive forces and mechanical failure in regions where lamellae bifurcate.
Meek
Keith M
KM
School of Optometry and Vision Sciences, Cardiff University, UK.
Tuft
Stephen J
SJ
Huang
Yifei
Y
Gill
Paulvinder S
PS
Hayes
Sally
S
Newton
Richard H
RH
Bron
Anthony J
AJ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003094:Collagen / Q000737:chemistry* / Q000378:metabolism*; D003319:Corneal Stroma / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D007640:Keratoconus / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D014961:X-Ray Diffraction
D003094:Collagen