Estudo das propriedades morfológicas e mecânicas de córneas humanas via microscopia de força atômica

Abstract

In the present work the morphological properties of the corneal tissue are investigated by means of Atomic Force Microscopy. In particular, the corneal tissues of 20 and 60 years old human beings are compared in order to shed light on the dependence on the age. The normal cornea is a layered, avascular structure in which an outer epithelium and an inner endothelium surround the central stroma. The transversal cross-sections of the central and peripheral parts of the cornea were examined in order to study the differences between these regions and their respective layers, especially the stroma, which is responsible for 90% of the thickness of the cornea. Some show of force curves were obtained. They show the stiffness of the tissue to which the probes were used. However AFM imaging was a difficult task due to the large number of fibers occuring especially in the central part. In literature it is known that the (normal) cornea has an anisotropic structure of collagen fibers, but the arrangement of these fibers is still not well understood. The results of this study show the existence of fibers which are arranged in a "Y", wherein a fiber seems to give rise to another. Our study becomes important in that contribute to the understanding of corneal fibril formation, which is closely related to its transparency.