PURPOSE. The purpose of this study was to evaluate the dispersion of intravitreally injected solutions and investigate the influence of varying injection techniques.METHODS. This was a prospective study using enucleated porcine eyes and ultra-highresolution computed tomography (UHRCT) scanning to visualize iomeprol intravitreal dispersion. Sixty eyes were divided over 12 different groups according to the injection procedure: fast (2 seconds) or slow (10 seconds) injection speed and needle tip location (6-and 12-mm needle shaft insertion or premacular tip placement verified by indirect ophthalmoscopy). For each of these combinations, eyes were either injected with the combination of V20I (which is an analogue of ocriplasmin) and iomeprol or iomeprol alone. Distance to the macula and volume measurements were performed at 1, 2, 3, and 5 hours after injection.RESULTS. The measured contrast bolus volume increases slowly over time to an average of 0.70 (P ¼ 0.03), 1.04 (P ¼ 0.006), and 0.79 (P ¼ 0.0001) cm 3 5 hours after the injection for the 6-mm needle shaft insertion, 12-mm needle shaft insertion, and premacular needle tip placement, respectively. The distance to the macular marker was significantly lower for premacular needle tip placement injections compared with 6-and 12-mm needle shaft insertion depths.CONCLUSIONS. Ultra-high-resolution computed tomography with three-dimensional reconstruction offers the possibility to study the dispersion of intravitreally injected solutions in a noninvasive manner. Intravitreal premacular solution delivery is possible with an indirect ophthalmoscope-guided injection technique and significantly reduces the time to reach the posterior pole in respect to 6-and 12-mm needle insertion depths. The speed of injection does not influence dispersion significantly.
PurposeThe extent of activity of an intravitreal injected drug is linked to its dispersion within the vitreous body. Researchers have been trying to visualize dispersion of intravitreal injected solutions using Indian ink or fluorescein, either with subsequent dissection or with endoillumination, both invasive methods that could influence the dispersion pattern. Therefore, this pilot study aims at investigating and identifying the best minimal invasive imaging method for visualizing the dispersion of an intravitreal injected solution.MethodsTo determine the optimal imaging concentration, a series of 5 enucleated porcine eyes were injected with 0.1 cc of 100%, 50%, 25%, 20% and 10% standard iodium contrast medium, respectively. Injections were made using a standard 1 cc syringe and 30 gauge needle at 3.5 mm from the limbus aiming at the center of the globe. Subsequently, the dispersion of the contrast agent was monitored using high resolution imaging methods: mammography and ultra high resolution computed tomography (UHRCT). For the latter, 3D reconstructions were rendered.ResultsA 1:10 dilution mixture combined optimal visualization contrast with low viscosity of the injection solution using radiographic ultrahigh resolution mammography. Both mammography and UHRCT images were taken from two eyes; one with a slow injection, the other with a fast injection.Conclusions3D reconstructed UHRCT images were favored over 2D mammography images for dynamic imaging of the intravitreal solution dispersion.
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