Modeling human corneal polarization properties and comparison with PS-OCT measurements

Polarization sensitive optical techniques such as Scanning Laser Polarimetry (SLP) or Polarization Sensitive Optical Coherence Tomography (PS-OCT) must take into account corneal polarization changes when imaging the eye fundus. Information about corneal structure is also basic in the diagnosis of corneal disorders. Histological analysis shows that cornea is layered, with fibrils oriented at varying angles. However, this information does not refer to fibril orientation in a macrostructural sense. In this work, we propose a corneal structural model with different fibril arrangements and compare them with in vivo and in vitro PS-OCT measurements. The model is based on a stack of lamellae, represented by Jones theory. Each lamella has a preferred fast axis orientation according to the fibril structure and a birefringence. Optical radiation is parallel to the eye optical axis. A third of the lamellae are arbitrarily oriented. Several fibril configurations were modeled: preferentially horizontal and vertical fibrils; preferentially vertical and radial fibrils; circularly and radially oriented fibrils; and a configuration in which fibrils form arcs that join opposite points of a cross defined over the corneal surface. We also modeled the rotation of the previous configurations and compared them with PS-OCT measurements of in vitro tilted corneas.