Birefringence of a medium of tenuous parallel cylinders.

A general expression for the form birefringence of a medium of parallel cylinders of arbitrary sizes and separations has been developed. It is necessary to assume only that the refractive index fluctuations through the medium are sufficiently small. This expression has been evaluated for a model of retinal nerve fiber layers. The birefringence of these layers has considerable potential as a diagnostic tool since it is expected to be sensitive to structural changes associated with retinal pathologies. Although accurate measurements of this birefringence have not yet been carried out they appear to be feasible or may soon be so.