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 µL/∂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).