Investigation of vitreous substitutes was begun by Cibis et al 1 more than forty years ago. Originally, both lighter-than-water silicone oil and heavier-than-water vitreous substitutes were studied. The former demonstrated good clinical application. 2 The first heavier-than-water vitreous substitute, fluorosilicone oil, also proved effective intraoperatively and postoperatively, but its poor ocular tolerance and high viscosity limited its usefulness. 3