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Leslie Wilson, Woo June Choi, Ruikang K Wang, Russell N Van Gelder, Kathryn L Pepple; Comparison of Spectral Domain and Swept Source Optical Coherence Tomography in a Rat Model of Anterior Uveitis. Invest. Ophthalmol. Vis. Sci. 2016;57(12):2189.
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© ARVO (1962-2015); The Authors (2016-present)
Due to the size of rodent eyes, features of inflammation are difficult to assess without sacrificing the animal for tissue analysis. In this pilot study, we test optical coherence tomography (OCT) as a non-lethal assay of anterior segment inflammation in rat eyes. Furthermore, we aim to test spectral domain OCT (SD-OCT) and swept source OCT (SS-OCT) to determine which imaging platform provides superior images for analysis.
Uveitis was induced in female Lewis rats (n=3) by a subcutaneous injection of 0.1 mg killed mycobacterium tuberculosis H37Ra extract suspended in adjuvant. Seven days later, the right eye was injected with 5mg of the extract in PBS. Right eyes were imaged using SD-OCT and SS-OCT prior to intraocular injection (Day 0) and at peak inflammation (Day 2). After day 2 imaging, the animals were sacrificed and eyes were analyzed by histology. Structural signs of inflammation, including increased anterior chamber (AC) cells, presence of pupillary membrane, and ciliary body (CB) inflammation, were identified on SD an SS images and scored. Cell counts obtained from SD and SS OCT images were compared.
Structural signs of AC inflammation that were identified by the gold standard assay of histology were detectable by both OCT modalities. Qualitatively, SD-OCT imaged a smaller area of the eye, but at higher resolution, allowing for better detection of AC cells. There were significantly more cells (p=0.02) counted in SD-OCT images (Avg. = 374) than in SS-OCT images (Avg. = 318). Additionally, the CB was visualized with the highest clarity on SD-OCT images taken at the limbus. This structure was not clearly resolved by SS-OCT. SS-OCT was superior in providing a whole eye image in one scan. However, the lens occupied 50% of the image, and most of the posterior segment was not visualized due to shadowing from anterior structures, even with pupillary dilation.
Both SD-OCT and SS-OCT identify features of inflammation in a rat model of uveitis. SD-OCT allowed for higher resolution images and improved ability to detect AC cells and resolve CB structural changes. SD-OCT is the preferred imaging modality for generating quantifiable images in rat anterior uveitis. In the future, SD-OCT could be used as a non-lethal assay allowing for repeat analysis in a single animal over time and in response to treatment.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
SD-OCT vs. SS-OCT imaging in rat anterior uveitis
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