A numerical model of light adjustable lens
We model numerically the mechanical effects of UV induced photo-polymerization in elastomeric artificial lens. The elastomer is originated upon cross-linking of a silicone matrix. UV irradiation of one side of the lens polymerizes selectively a photosensitive macromer, causing local variations of its concentration. The subsequent diffusion of macromers from high concentration to low concentration zones modifies the shape of the lens and thus its dioptric power. In vitro experiments on artificial lens showed that the power change is dependent on UV exposure time, irradiation intensity and light pattern. With the aim to define a numerical tool able to predict the dioptric power adjustment as a function of the UV irradiation parameters, we setup a purely mechanic finite element model of the lens, adopting a hyperelastic material model embedded with eigen-deformations. Numerical simulations of axis-symmetric irradiation closely reproduced the experimental results, in terms of both lens geometry and dioptric power, for positive, negative and lock-in corrections.
© Springer-Verlag 2009. Received: 20 September 2008 / Accepted: 25 December 2008 / Published online: 24 January 2009. We greatly acknowledge the financial support of Calhoun Vision, Inc. Pasadena, California. We thank Dr. Chris Sandstedt for the kind and helpful assistance on technical issues and for providing the experimental data.