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Meoghan E MacPherson, Vivian Lee, Joshua T Davis, Paul David Hamilton, Nathan Ravi, William J Foster; Short-term in vivo evaluation of in situ forming hydrogels as vitreous substitute candidates. Invest. Ophthalmol. Vis. Sci. 2016;57(12):4450.
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© ARVO (1962-2015); The Authors (2016-present)
Despite significant advances in viteroretinal disease treatment, contemporary vitreous substitutes are neither biomimetic nor provide a definitive long-term solution. With critical need for a permanent vitreous prosthetic, we evaluated the in vivo bioperformance of three injectable poly(acrylamide)/acrylic acid/2-acryloyl-phosphorly-choline (Am/AA/2-APC) in situ forming hydrogels in a one-week rabbit model.
Twenty-seven Dutch-Belted rabbits were divided into four groups: 20% acrylic acid hydrogel (20AA, n=7), 10% acrylic acid hydrogel (10AA, n=7), 10% acrylic acid with 2-APC hydrogel (10AA+2-APC, n=7), and silicone oil (n=6). Baseline measurements were established through complete ophthalmic examination with intraocular pressure (IOP) and electroretinography (ERG). A standard pars-plana vitrectomy was performed on the right eye utilizing a chosen material, with the left eye serving as control. On day seven, a complete ophthalmic examination and ERG was conducted prior to enucleation of both eyes. Globes were fixed for histologic examination. Following gross examination, two consecutive sections were obtained from each calotte, stained with hematoxylin-eosin (H&E) and reviewed by an ocular pathologist. A 5% significance level was used for analysis of IOPs and ERG b-wave ratios.
Ophthalmic examinations revealed no evidence of inflammation, hemorrhage, vitritis, uveitis, retinitis, or endophthalmitis. Excluding postoperative silicone oil, no statistically significant difference was found between experimental and control eye IOPs. No difference in IOP was found at baseline or postoperatively between materials. While all materials experienced small reductions in single flash b-wave ratios, there was no statistically significant difference at baseline or postoperatively. Histological findings indicate silicone oil was well tolerated with no significant inflammation. Chronic inflammation secondary to foreign material was present in both hydrogels lacking 2-APC; 20AA is likely retinotoxic, while 10AA shows a similar but less robust response. In contrast, the 10AA+2-APC hydrogel predominantly elicits a rare to mild inflammatory response.
Our results indicate that seven days postoperatively, a 10% acrylic acid with 2-APC hydrogel looks promising as a biomimetic vitreous substitute. Analysis of the long-term studies is currently underway.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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