Optical Coherence Tomography: Imaging Visual System Structures in Mice.

Optical coherence tomography (OCT) enables micron-scale resolution of structural anatomy, thereby making OCT a valuable tool for addressing ophthalmologic and neurologic inquiries. Although the murine eye and its structures are very small and offers challenges for OCT imaging, OCT can be used to monitor retinal layer thickness in healthy and diseased retinas in murine lines in vivo longitudinally. Thus, OCT can provide insights into disease severity and treatment efficacy. This chapter describes the use of OCT as a powerful non-invasive imaging technology for high-resolution retinal imaging and retinal thickness quantification in rodents.

Bright-Field Imaging and Optical Coherence Tomography of the Mouse Posterior Eye.

Noninvasive live imaging has been used extensively for ocular phenotyping in mouse vision research. Bright-field imaging and optical coherence tomography (OCT) are two methods that are particularly useful for assessing the posterior mouse eye (fundus), including the retina, retinal pigment epithelium, and choroid, and are widely applied due to the commercial availability of sophisticated instruments and software. Here, we provide a guide to using these approaches with an emphasis on post-acquisition image processing using Fiji, a bundled version of the Java-based public domain software ImageJ. A bright-field fundus imaging protocol is described for acquisition of multi-frame videos, followed by image registration to reduce motion artifacts, averaging to reduce noise, shading correction to compensate for uneven illumination, filtering to improve image detail, and rotation to adjust orientation. An OCT imaging protocol is described for acquiring replicate volume scans, with subsequent registration and averaging to yield three-dimensional datasets that show reduced motion artifacts and enhanced detail. The Fiji algorithms used in these protocols are designed for batch processing and are freely available. The image acquisition and processing approaches described here may facilitate quantitative phenotyping of the mouse eye in drug discovery, mutagenesis screening, and the functional cataloging of mouse genes by individual laboratories and large-scale projects, such as the Knockout Mouse Phenotyping Project and International Mouse Phenotyping Consortium.