Abstract
Purpose: :
Heavy silicone oil substitutes have been developed with limited success; however, their widespread use has been restricted secondary to inflammation and subsequent development of proliferative vitreoretinopathy. We present a new candidate heavy silicone oil without the use of fluorine, perfluorocarbons, or olefins for use in vitreoretinal surgical applications.
Methods: :
Denser alkyl side chains were utilized on a siloxane backbone to increase the specific gravity of silicone oil to greater than 1.0033 g/cc (density of BSS at 37 degrees C). Polymers were isolated and purified through fractional precipitation and solvent evaporation and then heat sterilized. The purified polymers were then evaluated by gel permeation chromatography and 1H-NMR spectroscopy. Interfacial surface tension was measured by the pendant drop method. Biocompatibility of the heavy silicone oil was tested in a 5-week preliminary pilot study in a New Zealand white rabbit eye. A core vitrectomy and heavy silicone oil fill were performed without the use of post-operative anti-inflammatory agents. ERG measurements, ophthalmic exams, and histology were performed during the study to evaluate biocompatibility.
Results: :
The isolated heavy silicone oil was purified to > 99% purity and yielded a density of 1.104 g/cc, a viscosity < 1000 centistokes, and an average interfacial surface tension value of 68 mN/m (clinical grade 1000 CS silicone oil had a measured interfacial surface tension of ~ 45 mN/m). The final product was an optically transparent clear oil which demonstrated in vitro stability in BSS for 6 months without signs of emulsification. A 5-week pilot in vivo study in one rabbit eye demonstrated no observable emulsification or inflammation on direct visualization, stable ERG waveforms, and minimal vitreous inflammation on histology with normal retinal architecture.
Conclusions: :
Heavy tamponade agents are an emerging area of development within vitreoretinal surgery that could have numerous applications. We report an initial pilot study demonstrating a new candidate polymer yielding favorable results. We hope to expand our initial pilot study to more thoroughly assess this new candidate heavy silicone oil.
Keywords: retina • vitreous substitutes • vitreoretinal surgery