Table 2.

Measurements of Skin Viscoelasticity Obtained From a Cutometer^®

Measurand	Description
Immediate deformation/skin extensibility (Ue)	Quick response to force; change in shape from baseline in response to force (suction)
Delayed distention (Uv)	Incremental change in shape or viscous “creep” that occurs after the quick elastic response (Ue) reacting to force over time
Final deformation (Uf)	Total viscoelastic deviation of the skin from baseline in response to force over time (Ue + Uv)
Immediate retraction (Ur)	Quick return of the skin toward baseline when force is removed
Final retraction (Ua)	Ultimate return of the skin from Uf toward baseline after removal of force. Final retraction is Ur plus the viscous “downward incremental creep” and final measurement of deformation before another measurement cycle begins
Gross elasticity (R2)	Ratio (Ua/Uf) that includes the viscous changes of the skin for both deformation and retraction. Includes effects of both elasticity of the skin’s solid components {elastic fibers, etc.) and viscosity from the liquid content of the skin. Variable viscous retraction rates may result in an incomplete measurement of skin function with this value
Net elasticity (R5)	Ratio (Ur/Ue) that excludes viscous changes, focusing the measure on the solid components of the skin
Biological elasticity (R7)	Ratio (Ur/Uf) that includes measures of viscoelastic deformation on application of force and elastic retraction on release; provides a practical means for evaluating the viscous and anatomical components of skin elasticity