Analysis of the central corneal birefringence with double-pass polarimetric images

Abstract

A double-pass imaging polarimeter has been used to compute the central corneal birefringence axis and retardation in a group of 22 eyes of different ages. Sets of four retinal images corresponding to independent polarisation states in the analyser unit were recorded. From the intensities at the image central area the corneal polarimetric parameters were computed using the Stokes–Mueller formalism. Although the (slow) axis of the central cornea presented individual differences, it was mostly lying along the nasal-downward direction. Corneal retardation also presented a broad distribution. Neither the axis nor the retardation was correlated with age. There was a significant correlation between age and the intensity at the central area of the images. This technique might be a useful tool when combined with clinical instruments oriented to glaucoma detection, which include corneal compensation for polarimetric retinal imaging.