Polarization-sensitive optical coherence tomography imaging of the anterior mouse eye

Abstract

Polarization-sensitive optical coherence tomography (PS-OCT) enables noninvasive, high-resolution imaging of tissue polarization properties. In the anterior segments of human eyes, PS-OCT allows the visualization of birefringent and depolarizing structures. We present the use of PS-OCT for imaging the murine anterior eye. Using a spectral domain PS-OCT setup operating in the 840-nm regime, we performed in vivo volumetric imaging in anesthetized C57BL/6 mice. The polarization properties of murine anterior eye structures largely replicated those known from human PS-OCT imagery, suggesting that the mouse eye may also serve as a model system under polarization contrast. However, dissimilarities were found in the depolarizing structure of the iris which, as we confirmed in postmortem histological sections, were caused by anatomical differences between both species. In addition to the imaging of tissues in the anterior chamber and the iridocorneal angle, we demonstrate longitudinal PS-OCT imaging of the murine anterior segment during mydriasis as well as birefringence imaging of corneal pathology in an aged mouse.

Retinal analysis of a mouse model of Alzheimer’s disease with multicontrast optical coherence tomography

“…Care must also be taken that eye drops are rigorously applied throughout the experiment to ensure a cataract does not form while the animal is under anesthesia. 80 The disorganisation of the OPL/ONL structure observed in three transgenic mice and three wildtype mice was not expected from current literature regarding this mouse model. Previous studies in both the mouse 81 and the human 82 have attributed similar OPL/ONL splitting to mutations in the CACNA1F gene encoding for the L-type calcium channel Ca v 1.4 which is also expressed in the outer nuclear layer of the mouse retina.…”

Signal averaging improves signal-to-noise in OCT images: But which approach works best, and when?

“…This noise bias impacts the measured SNR, in particular for weak signals. Akin to noise offset removal in PS-OCT processing [39,40], we performed SNR calculations with noise bias correction in sections 2.3.4 and 3. By using this modified approach, a superior SNR performance was always observed for complex averaging, regardless of the input signal strength.…”

“…In this section, we introduce and evaluate an SNR analysis with noise bias correction. A similar approach has for instance also been used by Makita et al [39] and recently been modified by our group [40] to correct for noise contributions in PS-OCT images and improve the computation of the degree of polarization uniformity for weak signals. To some extent, this SNR with noise bias correction resembles the SNR definitions in Refs.…”

Three-dimensional visualization of opacifications in the murine crystalline lens by in vivo optical coherence tomography

“…The disruption of these fibrillar structures and the aggregation of cells are the main cause of cataracts and opacifications [53]. The extension of our device to a polarization sensitive OCT system might enable the visualization of depolarization produced by cataractous lesions [54,55]. Since the basic principle of many imaging methods currently used for cataracts investigations are based on light scattering, our recently proposed bright and dark-field (BRAD) OCT technique might also be an interesting candidate for investigating scattering properties and cataractous lesions in the crystalline lens [24,28].…”