Polarized light propagation in corneal lamellae

The propagation of polarized light through the cornea is affected by the or ientations of the corneal lamellae and by the refractive imbalance between the collagen fibrils and the ground substance. Thus, well-designed measurem ents and analyses of polarized light propagation through the cornea can be used to obtain information regarding the cornea's lamellar and fibrillar st ructures. This paper shows that, for the rabbit, measured values of the opt ical parameters strongly suggest that the distribution of lamellae orientat ions is not random, but has one (or two) preferred orientation directions. Also, there is considerable evidence that collagen is intrinsically anisotr opic. The Weiner formula gives the effective birefringence of an assembly o f parallel isotropic fibrils and its generalization to the case of anisotro pic fibrils is presented. Finally, calculations based on preferred orientat ion models having lamellae composed of anisotropic fibrils show that compar ison with experimental values can yield structural information.