PERFLUOROCARBON LIQUID MANIPULATION OF HIGH-DENSITY INTRAOCULAR FOREIGN-BODIES

Background: Perfluorocarbon liquids (PFCLs) are useful for floating va rious materials off the posterior retina during vitreoretinal surgery. It is generally assumed that buoyancy forces restrict this use to obj ects with specific gravity lower than that of PFCLs. Methods: We teste d potential intraocular foreign body materials with specific gravities ranging from 1.1-8.7. The relative affinities of each material for sa line and PFCL (specific gravity 1.94) were determined. For each materi al, we then tested the ability of several specimens of increasing surf ace/volume ratio to float at the saline-PFCL interface in a glass beak er. Results: All materials with specific gravity higher than PFCL demo nstrated a greater affinity for saline than for PFCL. Specimens of eac h of these dense materials floated at the saline-PFCL interface, provi ded that the surface/volume ratio of the specimen was above a critical value. The critical surface/volume ratio for each material was direct ly proportional to its specific gravity. Conclusions: PFCLs may be use ful for manipulating a variety of intraocular foreign bodies, even tho se with specific gravities higher than PFCL. Surface forces, in additi on to buoyancy, govern the disposition of small foreign bodies at the saline-PFCL interface.