Sudhalkar H A, Johnson M W
W.K. Kellogg Eye Center, Department of Ophthalmology, University of Michigan School of Medicine, Ann Arbor 48105, USA.
Retina. 1998;18(5):460-5. doi: 10.1097/00006982-199809000-00013.
Perfluorocarbon liquids (PFCLs) are useful for floating various materials off the posterior retina during vitreoretinal surgery. It is generally assumed that buoyancy forces restrict this use to objects with specific gravity lower than that of PFCLs.
We tested potential intraocular foreign body materials with specific gravities ranging from 1.1-8.7. The relative affinities of each material for saline and PFCL (specific gravity 1.94) were determined. For each material, we then tested the ability of several specimens of increasing surface/volume ratio to float at the saline-PFCL interface in a glass beaker.
All materials with specific gravity higher than PFCL demonstrated a greater affinity for saline than for PFCL. Specimens of each of these dense materials floated at the saline-PFCL interface, provided that the surface/volume ratio of the specimen was above a critical value. The critical surface/volume ratio for each material was directly proportional to its specific gravity.
PFCLs may be useful for manipulating a variety of intraocular foreign bodies, even those with specific gravities higher than PFCL. Surface forces, in addition to buoyancy, govern the disposition of small foreign bodies at the saline-PFCL interface.
全氟碳液体（PFCLs）在玻璃体视网膜手术中可用于使各种物质漂浮于视网膜后部。一般认为浮力将这种应用限制于比重低于PFCLs的物体。
我们测试了比重范围为1.1至8.7的潜在眼内异物材料。确定了每种材料对盐水和PFCL（比重1.94）的相对亲和力。然后，对于每种材料，我们测试了几个表面积/体积比不断增加的样本在玻璃烧杯中盐水 - PFCL界面处漂浮的能力。
所有比重高于PFCL的材料对盐水的亲和力均大于对PFCL的亲和力。只要样本的表面积/体积比高于临界值，这些致密材料中的每种样本都会漂浮在盐水 - PFCL界面处。每种材料的临界表面积/体积比与其比重成正比。
PFCLs可能有助于处理各种眼内异物，即使是那些比重高于PFCL的异物。除浮力外，表面力也决定了小异物在盐水 - PFCL界面处的位置。
