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L. H. Lima, J. H. Oh, M. E. Thompson, J. Weiland, R. N. Agrawal, D. Eliott, M. S. Humayun; Poly-N-Isopropylacrylamide (pNIPAM) for Sclerotomy Closure. Invest. Ophthalmol. Vis. Sci. 2008;49(13):5976.
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To study the use of poly-N-isopropylacrylamide (pNIPAM) for sclerotomy closure with transscleral polymer cable
In initial studies, 50% poly-N-isopropylacrylamide (pNIPAM) liquid was applied on a patent 20-gauge sclerotomy in pigmented rabbits after a standard core vitrectomy and covered with conjunctiva during the test. In an acute study, pNIPAM was applied on the sclerotomies in 4 rabbit eyes, while the bottle height was kept constant at 70 mmHg for 1-2 hours. In the short term chronic study, pNIPAM was applied to the sclerotomy in 4 rabbits and the rabbits were followed up for 15 days, 1 month and 2 months. The animals underwent routine evaluation at regular intervals for intraocular pressure measurement (IOP), indirect ophthalmoscopy, external and fundus photography and fluorescein angiography (FA). Secondly, pNIPAM was also applied to test closure of enlarged sclerotomy with a transscleral polymer cable in an acute setting in 2 rabbits. In one, pNIPAM alone was used to close the sclerotomy with a polymer cable. In another, interrupted 6-0 sutures supplemented pNIPAM for closure.
All rabbits underwent successful closure of the sclerotomies wound in the first set of experiments. pNIPAM created sufficient wound closure in all cases. There were no complications in the acute setting (low IOP) or on follow up (low IOP, endophthalmitis or retinal folds/detachment, etc.). No leakage was observed through the sclerotomies while the bottle height was kept around 70 mmHg. The test was conducted with the scleral temperature at both above 32 degree Celsius (C) and when allowed to stabilize to operating room temperature (~ 20 degree C). FA or external photography did not reveal any significant findings. For the transscleral cable study, leakage occurred at 40 mmHg when no sutures were taken. With added sutures, sclerotomy leaked at 60 mmHg.
pNIPAM can be used for routine sclerotomy closure, without significant side-effects. It can also close an enlarged sclerotomy even in the presence of a transscleral cable in an acute setting. Further evaluation is in progress to study long term outcomes
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