Contact-Based Stiffness Sensing of Human Eye. - Yuichi Kurita; Roland Kempf; Yoshichika Iida; Jumpei Okude; Makoto Kaneko; Hiromu K. Mishima; Hidetoshi Tsukamoto; Eiichiro Sugimoto; Seiki Katakura; Ken Kobayashi; Yoshiaki Kiuchi (IEEE Trans. Biomed. Eng., 2008)