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Brian C. Gilger, Gabriela S. Seiler, Jacklyn H. Salmon, Rebecca Mantuo, Steven Feingold, Paul A. Dayton; Distribution of Contrast Medium after Injection into the Anterior Suprachoroidal Space Using 2D and 3D Ultrasound in Pig Eyes. Invest. Ophthalmol. Vis. Sci. 2011;52(14):3245.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the local effects and posterior distribution of injections made into the anterior suprachoroidal space (SCS).
Scleral incisions were made 5 mm posterior to the superior limbus to expose the SCS in fresh porcine cadaver eyes. A 27-gauge cannula was placed 1 mm into the SCS and the scleral incision sealed with tissue adhesive. High frequency ultrasound (US)(50 mHz) was used to image the SCS effect and distention from 250, 500, 800 and 1000 uL of PBS. Microbubble contrast agent (250, 500, and 800 uL; Targestar-P, Targeson Inc., San Diego, CA) was injected into the anterior SCS and imaged using a contrast-enhanced 2D b-mode US (Mylab70, Biosound Esoate, Inc., Indianapolis, IN). Flow characteristics of the contrast agent in the SCS and percentage of maximal distribution in the SCS of contrast agent was determined in the sagittal US plane. Contrast agent (250ul ) was injected into the anterior SCS, as described above, and 3D US imaging (Acuson Sequoia, Siemens, Malvern, PA) was also performed to determine distribution of the contrast in the SCS.
Maximum mean (±SD) distention, as visualized by high-frequency US, of the SCS from injection with 250 µl PBS was 1.57±0.48 mm; 500 µl PBS was 2.57±0.52 mm, 800 µl PBS was 2.98±0.37 mm, and 1000 µl PBS was 3.28±0.57 mm. Using 2D US, after injection the contrast was visible initially in the SCS at the injection site, then at the opposite ventral anterior SCS, and finally at the posterior SCS. The overall mean time after injection for contrast to appear at the opposite and posterior SCS was 7.8 ± 4.6 and 7.7 ± 4.6 seconds, respectively. In the sagittal 2D US section, contrast agent was visible in a mean 24.0 to 27.2% of the entire SCS when injected with 250, 500, or 800 µl contrast, however 10 out of 12 eyes (83.3%) had contrast that reached the posterior pole of the eye. In 3D images, contrast medium occupied 39.0% to 52.1% of the entire SCS.
These results suggest that the SCS can expand, in a dose-dependent manner, to accommodate various volumes of injected fluid. We have also demonstrated that it is possible to image the SCS with an US contrast agent and determine volume of distribution. Furthermore, these results support our hypothesis that a single anterior SCS injection with a volume as low as 250 uL can reach the ocular posterior segment. These results warrant further development of SCS injections for treatment of disease of the ocular posterior segment.
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