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Marco Augustin, Stanislava Fialova, Roberto Plasenzotti, Michael Pircher, Christoph K Hitzenberger, Bernhard Baumann; Multi-Functional OCT for Long-Term Study of Retinal Changes in a VLDLR Mouse Model. Invest. Ophthalmol. Vis. Sci. 2016;57(12):2194.
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© ARVO (1962-2015); The Authors (2016-present)
To demonstrate the feasibility of using multi-functional optical coherence tomography (OCT) for identifying and tracking retinal changes in three contrast channels – Reflectivity, Polarization Sensitive (PS) and Motion Contrast. To show long-term functional and morphological changes in the very-low-density-lipoprotein receptor (VLDLR) mouse model.
A PS-OCT system was utilized to image the posterior eye of VLDLR mice. Three dimensional images, comprising 512 A-scans × 400 B-scans repeated 5 times at each B-scan position, covering a field of view of 28° × 28° (corresponds to approximately 1 × 1 mm) were acquired. OCT angiography based on motion contrast was calculated from the phase variance between each set of repeated B-scans. Averaging of repeated B-scans was used for speckle noise reduction in the reflectivity images. For degree-of-polarization-uniformity (DOPU) images, a 3D temporal kernel of 3 × 9 × 5 (z × x × t) was used. To differentiate between different slabs of the retina, an automated layer segmentation algorithm based on graph theory was developed. This algorithm segmented five borders/layers in the retina and enabled the assessment of changes in different slabs. Contrast specific projections within these slabs, e.g. minimum DOPU projection, were used to generate maps highlighting various aspects during disease progression over time. Disease progression was studied in both eyes of 8 VLDLR mice within the age of 26 to 257 days. The mice were imaged every 4 to 6 weeks.
Follow-up measurements and analysis of VLDLR multi-functional image data revealed visible changes in all three contrast channels. Multiple lesions were present in all 16 eyes at the initial measurement in the reflectivity images. The lesions were tracked over time within two different positions around and close to the optic nerve head. Vascular changes such as anastomosis of retinal and choroidal vessels were observed. Depolarizing deposits in the inner retina region were noticed in en-face DOPU maps with disease progression.
In this work, we demonstrated the potential of multi-functional OCT offering threefold image contrast. In the VLDLR mouse model, severe pathological retinal changes were revealed in each of the investigated contrast channels. These retinal changes can be tracked and observed over time in longitudinal studies.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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