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Nathan Ravi, Jessica Struckhoff, Ying-Bo Shui, Sruthi Santhanam, Paul David Hamilton; Evaluation of the biocompatibility of an in situ forming hydrogel vitreous substitute in vivo: a one month study. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5824.
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© ARVO (1962-2015); The Authors (2016-present)
Many vitreoretinal diseases necessitate removal and replacement of the vitreous. Current vitreous substitutes leave much room for improvement. We developed a two-component in situ forming hydrogel vitreous substitute to mimic the structure and function of the native vitreous. The components are thiolated gellan, an analogue of collagen, and thiolated poly(methacrylamide-methacrylate), an analogue of hyaluronic acid. We performed a one month in vivo study to test its biocompatibility in rabbit eyes.
Thirty-two Dutch-Belted rabbits were used. Two sets received formulations of the two-component hydrogel (n=11 each) and the third set received silicone oil (n=10). A modified two port partial pars-plana vitrectomy was performed on the right eye of each rabbit followed by the injection of one of the three materials. Our substitute forms an ionic gel as it cools from 42oC to physiological temperature and then forms covalent bonds through oxidation. Baseline examinations prior to surgery include slit lamp assessments (SLA), measurements of intraocular pressure (IOP) and electroretinography (ERG). After surgery, IOP and SLA were performed on day one, four and seven. At one month, ERG, IOP, SLA and optical coherence tomography (OCT) were performed. Eyes were enucleated, fixed and H&E stained for histology.
SLA showed no evidence of inflammation in the anterior chamber at day 1, 4, 7 or 30 in any experimental group. IOP measurements remained in the normal range for all experimental groups and control (Figure C). Preliminary ERG findings displayed similar response between the experimental and control eyes. OCT analysis of the retinal layers showed no retinal detachment (Figure A). Histology revealed no significant inflammation caused by any of the experimental groups (Figure B). In addition, in two cases of a retinal hole occurring during surgery, the hydrogel was able to tamponade the retina and prevent any retinal detachment from developing.
This in situ forming hydrogel exhibits high in vivo biocompatibility after one month duration in the rabbit eye. The hydrogel maintains optical clarity and physiological IOP with no evidence of inflammation. Retinal layers remained intact and retinal activity appears normal.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
(A): OCT at one month exposure. (B): Histology from an eye receiving Formulation 1. (C) IOP measurements.
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