Viscoelastic substances are used in cataract surgery to provide better control during the operation. They have five main characteristics - cohesiveness, viscosity, elasticity, adhesiveness, and pseudoplasticity. There are two types - cohesive viscoelastic substances which are highly viscous and dispersive substances which are less viscous. Healon5 is an example of a viscoadaptive substance that can act as both cohesive and dispersive depending on the flow in the anterior chamber. Viscoelastic substances are used for maintaining space in the anterior chamber, capsulorhexis, hydrodissection, phacoemulsification, irrigation/aspiration, and capsular bag filling during cataract surgery