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S. W. Crafoord, F. K. Ghosh, S. Andreasson; The Use of a Polyacryl-Imide Hydrogel as Vitreous Replacement in a Rabbit Vitrectomy Model -Retinal Morphology and Function. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3665.
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© ARVO (1962-2015); The Authors (2016-present)
To develop an experimental protocol for evaluating possible damaging effect of artificial vitreous replacement substances, and to specifically test a polyacryl-imide hydrogel, clinically used in cosmetic reconstructive surgery.
A 20 gauge pars plana vitrectomy including posterior vitreous detachment was performed in the right eye of six pigmented rabbits. Approximately 1 ml of visco-elasthic gel (polyacryl-imide Bio-Alcamid TM) was thereafter injected into the vitreous space. Full-field ERG (ISCEV standard) and intraocular pressure (Tonopen) was measured pre-and postoperatively at regular intervals up to 28 days. At day 6 or 28 the rabbits were sacrificed and the eyes were gross examined, photographed and prepared for histologic examination with routine microscopy.
The visco-elastic gel was successfully injected through a 19 gauge needle and remained translucent throughout the postoperative period. The postoperative intraocular pressure was unchanged compared to preoperative values. All eyes displayed central retinal edema while the periphery appeared intact. ERG recordings showed a radical decrease in rod and cone derived B-wave amplitudes. Histologic examination confirmed varying degrees of edema combined with neuronal cell death within the retinal layers in the central part of the fundus while the peripheral part appeared intact. No evidence of inflammation was found.
Polyacryl-imide Bio-Alcamid TM displays favourable optic properties and does not seem to induce inflammation when used as a vitreous substitute. However, the hydrogel causes functional and morphological retinal damage when in direct contact with the inner retina. Possible pathological mechanisms include osmotic imbalance and direct toxic effects. The combined use of histology and ERG in the rabbit model of vitrectomy allows for detailed study of future vitreous replacement candidates.
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