Mechanical Performance of Hydrogel Contact Lenses Under Central Point Load.

Presenter: wei wang

Research Category: Engineering and Technology
PI: Kai-tak Wan

When a contact lens is under a central point load, its constitutive relation depends not only on the mechanical properties, such as elastic modulus of the hydrogel materials, but also the thickness variation along the meridional direction. Myopic lenses(d<0) are thinnest at the apex along the optical axis and thick out gradually along the meridian, while hyperopic lenses(d>0) are thicker at the apex. The Force-Displacement figure will be totally different between myopic and hyperopic lenses when vertical displacement of the external load increasing. The hyperopic lenses will show both curve increasing and decreasing in Force-Displacement figure, while myopic lenses always shows increasing curve. The decreasing curve will disappear when its diopter is changed from +8 to 0, and the stiffness of lenses for different diopter can be found. It shows that properties of contact lenses under central point load will be influenced by lens geometry dominantly, rather than the materials of the lens.