Purpose:
To determine the local mechanical properties of the porcinelens locally using a novel indentation device.
Methods:
Fresh porcine lenses were fixed in a 2% agarose gel. The lenseswere then sectioned across the equatorial plane (Fig. 1) orthe polar plane (Figs. 2, 3). The indenter applied a compressiveload normal to the lens’ exposed surface. The local elasticmodulus was computed from force-displacement data assuming incompressibility.
Results:
The young porcine lens exhibits a modulus gradient. The maximummodulus occurs at the center of the nucleus and decreases towardsthe periphery and the poles. The modulus depended heavily onthe direction of indentation, indicating anisotropic behavior.
Conclusions:
Detailed knowledge of the elastic gradient of the lens is essentialfor proper mechanical modeling of accommodation and presbyopia.It is also important to consider that the gradient may be anintegral part of the lens’ behavior in accommodation andmay vary significantly with age in humans, potentially contributingto presbyopia.
Keywords: intraocular lens • presbyopia • anterior segment