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Marco Augustin, Danielle J. Harper, Stanislava Fialová, Christoph K Hitzenberger, Bernhard Baumann; Retinal Characterization of SOD1-/- Mice by Multi-Functional OCT. Invest. Ophthalmol. Vis. Sci. 2018;59(9):5821. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Animal models used in basic ophthalmic research often lack an in-vivo morphological and functional characterization. Here optical coherence tomography (OCT) is used to describe the retinal phenotype of homozygous Cu,Zn-superoxide dismutase-1 (SOD1) knock-out mice. Differences between SOD1-/- mice and wildtype mice imaged in-vivo by a multi-functional OCT approach are investigated.
A multi-functional OCT system tailored for small animal retinal imaging was utilized, providing OCT angiography (OCTA) and polarization-sensitive (PS)-OCT contrast in addition to the conventional reflectivity information. SOD1-/- mice and wildtype mice serving as control were imaged within an age range of 25 to 33 weeks. A fundus region of 1 x 1 mm2 was scanned in the peripapillary region. PS-OCT as well as OCTA images were calculated. Seven retinal layers were segmented based on the reflectivity and PS-OCT contrast. The total and outer retinal thickness (outer plexiform layer to retinal pigment epithelium (RPE)), as well as the nerve fiber layer and the observed RPE thickness was determined and compared between wildtype and homozygous knock-out mice. Drusen-like lesions were identified in en-face projections of the posterior retina. The lesions were annotated manually and analyzed.
Four eyes each of the wildtype and the knock-out SOD1 mice were imaged. All eyes of SOD1-/- mice showed drusen-like lesions in the outer retina just above the retinal pigment epithelium, see Fig. 1b. A minimum of 5 lesions and a maximum of 30 lesions were found in the scanned field of view (m±s: 13.5 ±11.4). Control mice did not show any abnormalities. The total retina of SOD1-/- was on average thinner when compared to the wildtype mice. The most substantial difference was found in the thickness of the outer retina. A qualitative comparison of polarization contrast and OCTA images did not reveal any significant changes in the animals at this age.
Alterations in the retina of SOD1-/- mice were identified as drusen-like hyper-reflective structures. Retinal layering appears rather normal at this age, although a substantial thinning of the outer retina was determined. OCT has proven its potential to characterize the retina of a popular animal model with great detail and hence may be more extensively used for longitudinal imaging in preclinical retinal research.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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