Semifluorinated alkanes, R(F)R(H), have a perfluorocarbon and a hydrocarbon segment in the molecule. R(F)R(H) are physically, chemically and physiologically inert, colorless, laser stable liquids with substantially reduced densities--between 1.1 and 1.7 g/cm3--and very low surface and interface tensions. R(F)R(H) are useful for unfolding a retina or for permanent tamponade. They are soluble in perfluorocarbon liquids (PFCL), hydrocarbons and silicone oils. For the first time residues of silicone oil can be extracted from the eye because R(F)R(H) are solubilizers for PFCLs and silicone oils, so they can be used as solvents or solubilizers for drugs and medicaments. Therefore R(F)R(H) are excellent candidates for use in the ophthalmic field.