Fig 4. Transient viscous response to a step-wise compression-decompression cycle.

D is the distance between the silver surfaces (continuous line) in response to step displacements of the cantilever spring with length s = 10 μm (dashed line). The surfaces were first approached (‘in’–blue line) then retracted (‘out’–red line). The thickness of the corneal stroma was D₀ before compression and D_r after completely removing the compressive force. Arrows show: (A) last step before surface contact; (B, C) increasing compression with both surfaces in contact with the sample; (D) first step of surface retraction/decompression; (E) surface detachment upon retraction; (F) first step after detachment.