Design Considerations for Murine Retinal Imaging Using Scattering Angle Resolved Optical Coherence Tomography

Abstract

Optical coherence tomography (OCT), an optical imaging approach enabling cross-sectional analysis of turbid samples, is routinely used for retinal imaging in human and animal models of diseases affecting the retina. Scattering angle resolved (SAR-)OCT has previously been demonstrated as offering additional contrast in human studies, but no SAR-OCT system has been reported in detail for imaging the retinas of mice. An optical model of a mouse eye was designed and extended for validity at wavelengths of light around 1310 nm; this model was then utilized to develop a SAR-OCT design for murine retinal imaging. A Monte Carlo technique simulates light scattering from the retina, and the simulation results are confirmed with SAR-OCT images. Various images from the SAR-OCT system are presented and utility of the system is described. SAR-OCT is demonstrated as a viable and robust imaging platform to extend utility of retinal OCT imaging by incorporating scattering data into investigative ophthalmologic analysis.

Scattering Angle Resolved Optical Coherence Tomography Detects Early Changes in 3xTg Alzheimer's Disease Mouse Model

“…At the first surface of the cornea, the beam diameter is 0.7 mm. Given the axial length of the first cornea surface to the retina (3.3 mm in our model) and the weighted average of the index of refraction at 1310 nm (1.52), 43 the airy disk spot size is 24 µm and matches the value from the Zemax model (Zemax Development Corp., Kirkland, WA). The imaging system has an axial resolution of 11.7 µm in air, and the SAR-OCT imager is capable of detecting changes in bulk scattering angle up to 8° from a direct backscatter (0°).…”

“…The imaging system has an axial resolution of 11.7 µm in air, and the SAR-OCT imager is capable of detecting changes in bulk scattering angle up to 8° from a direct backscatter (0°). 43 …”

“…SAR-OCT instrumentation (Fig. 1) used for this study was previously described in detail by Gardner et al 43 A pathlength multiplexing element (PME) is introduced into the sample path at a position conjugate to the murine ocular pupil plane, and the PME encodes light scattered at lower and higher angles into three different pathlengths (Fig. 2).…”

“…Thickness measurements are not unique SAR-OCT features but are commonly used clinically to detect various diseases. Retinal sublayer thicknesses were obtained using a retinal segmentation algorithm outlined in Gardner et al 43…”

“…41 A specific subtype of angle-resolved OCT, termed scattering-angle-resolved OCT (SAR-OCT), positions an optical element in the pupil of the scanning system that pathlength-encodes angular information of backscattered light from the sample. [42][43][44][45] Each pupil region corresponds to a discrete optical pathlength that contains information from light that is incident or backscattered from a unique angular range. It has been demonstrated that SAR-OCT is sensitive to peripapillary variation in neuron size 44 and longitudinal changes in the hypoxic murine retina.…”