Lens Fluid Displacement and Accommodation

In this study, the biomechanics of the human lens geometry were numerically analyzed to quantitate micro-fluidic movement of lens fiber cells. Literature values were collected to develop a lens geometry paradigm related to optical output for both distant and near vision. We show that our numerical methods can successfully quantitate the micro-fluidic flow of lens fiber cells. Small changes in the lens fluidic movement responsible for optics are confined to a cortical volume element that appears compromised by lens modulus changes. The result imply that aging of the lens is accompanied by an almost constant inward equatorial movement at 21.2 0.002 microns/D. This creates a corresponding fluid volume of 1.74 0.17 L/D that is displaced per diopter of accommodation. A possible presbyopia lens treatment that achieves an acceptable accommodative end-point requires an estimate of the active pharmacological dose level. A therapeutic delivery requirement involving the entire lens mass may therefore be substituted by a treatment that targets the outer cortical region (or <2% of the total lens protein).