Circular polarization biomicroscopy: a method for determining human corneal stromal lamellar organization in vivo

The theory of polarization biomicroscopy is explored using Stokes vectors and Mueller matrices. It is established that circular polarization can be used to simultaneously detect birefringent elements at any orientation unlike orientation-sensitive techniques using linear polarized light alone. A method of biomicroscopy using circular polarized light is described and tested in a physical model. The method is then used to investigate the lamellar structure of human corneas in vivo in pairs of eyes of 38 subjects. An approximate confocal elliptic/hyperbolic distribution of stromal fibrils, presumed to be collagen, is clearly identified within central and intermediate areas of the cornea. All subjects tested demonstrate approximate mirror symmetry between pairs of eyes typically with a preferred orientation of central fibrils at approximately 15 degrees to the horizontal in a superotemporal-inferonasal direction.