F6H8 is a newly introduced vitreous substitute . With a density of 1.35 g / cm 3 , it is heavier than water so it can be used to tamponade inferior retinal breaks following pars plana vitrectomy . The study was conducted on 30 eyes all of whom had complicated retinal detachments involving the lower two quadrants . No obvious damage was recorded to the corneas , intraocular pressure , retina or optic disc . Dispersion during removal and cataract formation were the most important complications recorded when using this material.