THE INTEGRATION OF THE CORNEAL AND LIMBAL FIBRILS IN THE HUMAN EYE

The precise orientation of the collagen fibrils in human cornea and sc lera and the method by which these two areas fuse together at the limb us have never been determined, despite the importance of this informat ion. From a consideration of the mechanics of the system, fibril orien tation in the tissue has the potential to affect the curvature of the cornea so, by inference, refractive problems such as astigmatism invol ving an incorrect curvature of the cornea may be related to fibril ori entation. The high intensity and small beam size of a synchrotron x-ra y source has enabled us to study fibril orientation in post-mortem hum an cornea and sclera. Previously we have revealed two preferred direct ions of orientation in the cornea (Meek, K. M., T. Blamires, G. F. Ell iot, T. Y. Gyi, and C. J. Nave. 1987. Curr. Eye Res. 6:841-846) and a circumcorneal annulus in the limbus (Newton, R. H., and K. M. Meek. 19 98. Invest. Ophthalmol. & Visual Sci. 39: 1125-1134). Here we present the results of our investigation into the relationship between these t wo features. Our measurements indicate that the corneal fibrils orient ed in the two preferred directions bend at the limbus to run circumfer entially. On the basis of these results we propose a model as to how t he human cornea and sclera fuse together.