Fluidics and rheology in phaco surgery: what matters and what is the hype?

Rheology can be defined as the study of materials flow behaviour under applied deformation forces (stresses). Inside the eye during cataract surgery, transient or reversible deformation (elasticity) and permanent or irreversible deformation (flow) can both apply. Although the fluidics of modern phaco machines is an important part of this talk, there are a number of issues relating to flow and fluids in the eye during cataract surgery, which are unrelated to the machine, which can hinder or help the operating surgeon in removing a cataract. In addition, coping with the numerous complications, which can occur in the eye at the time of surgery, relies on an understanding of how fluidics and rheology can help to control the pressurised eye and bring the surgery to a successful conclusion.