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Nele Schneider, Kai Januschowski, Jose Hurst, Lisa Pohl, Maximilian Schultheiss, Christine Hohenadl, Charlotte Reither, Sven Schnichels, Martin Stephan Spitzer; Evaluation of a retinal detachment model for testing hydrophilic vitreous substitute. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):378. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Previously we showed that hydrophilic gels based on UV-crosslinked hyaluronate are well tolerated in rabbit eyes and thereby the lens usually remains clear. Consequently we created a rabbit model of retinal detachment to evaluate the efficacy of the gel, enabling us to evaluate this tamponade against silicone oil.
At first, we performed preoperative investigations on 2 groups consisting of 8 young rabbits (2 months old) using ERG, OCT and examining both eyes with the slit lamp and measuring the intraocular pressure. Thereafter, pars plana vitrectomy was performed in the right eye. Retinal detachment of one quadrant was induced by creating a small retinotomy near the vascular arcade and subretinal injection of balanced salt solution (BSS). Retinal hemorrhage was induced by a circumscribed vascular breach in the periphery of the vascular arcade. The retina was reattached by increasing the infusion pressure and the blood was washed out until the bleeding stopped. The retinal tear was treated by endolaser photocoagulation. At the end of the procedure the eye was either filled with 5000 cs silicone oil (after fluid air exchange) or the respective hydrogel was injected into the BSS filled eye until egress of the hydrogel of the opposite sclerotomy. After surgery, the right eye was reexamined at regular intervals and compared to the unoperated left eye by slit lamp examination, funduscopy and intraocular pressure measurements. The first OCT and ERG was made after one month. Afterwards both eyes were removed and processed for histology and immunohistochemistry with GFAP and Brn3a antibodies.
Seven of eight rabbits that received silicon oil, developed a partial or even total retinal detachment with pronounced proliferative vitreoretinopathy within the first two weeks after surgery. The ERG was completely extinguished in six rabbits, greatly reduced in one, and stayed unchanged in only one rabbit. In contrast, in the hydrogel group the retina stayed attached in 50% of the cases.
With the high rate of retinal detachments and proliferative retinopathy this model provides a good prerequisite for testing the efficacy of novel hydrogels as vitreous substitutes. Preliminary tests in this model point towards superior efficacy of cross-linked hyaluronate compared to silicone oil.
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