Viscoelastic substances in ophthalmology.

The desirable properties of a viscoelastic substance for ophthalmologic applications are intimately tied to its chemical and rheologic properties. This report describes the relevant rheologic properties (e.g., viscosity, viscoelasticity, pseudoplasticity, cohesiveness, and coatability) of the available viscoelastic substances and presents the general principles of their use as well as some specific technical aspects. In addition, the various uses of viscoelastic substances in ophthalmic surgery are outlined. There is no single ideal substance for all circumstances. With a knowledge of the rheologic properties of each substance, the ophthalmologist will be able to choose among the different ones as necessary to suit each clinical situation.