Polarization Sensitive Spectral Domain Optical Coherence Tomography Of Cataract Lenses

Abstract

Purpose: : To measure the polarization properties of human healthy and cataract lenses with a fiber based polarization sensitive OCT (PS-OCT) system.

Methods: : We used a fiber based polarization sensitive spectral domain optical coherence tomography system, using two CMOS line scan cameras. The system is based on polarization maintaining fibers and retrieves the backscattered intensity, retardation, optic axis orientation and Stokes vectors with a single A-scan per measurement location. The system has a sensitivity of 100dB. To further improve the signal to noise ratio averaging of 60 acquired B-scans of intensity and polarization data is performed. Additionally from these B-scans the degree of polarization uniformity (DOPU) is calculated (Instead of spatial averaging of Stokes vector data, temporal averaging over successive images is used).

Results: : We measured the lens of healthy volunteers and 6 cataract patients. In case of the healthy lens low backscattered intensity within the lens can be observed, as well as the lens capsule. The polarization sensitive images show, that signal backscattered from the lens does not alter the polarization state. The DOPU images show that the healthy lens is not depolarizing. In case of cataract lenses in areas of the opacity strong backscattered signal can be observed. The DOPU images show that in areas of the opacity depolarization can be observed. The amount of depolarization can vary strongly, typically stronger depolarization is found near the core of opacities.

Conclusions: : PS-OCT might be a useful method to quantify different cataract stages. Additionally PS-OCT could be used for characterizing different cataract types.

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • cataract