Masaru Yoshii1, Kenji Yanashima2, Akihiko Yoshioka3. 1. Eye Clinic, National Rehabilitation Center Hospital for the Disabled, Tokorozawa, Japan. yosii@rehab.go.jp. 2. Eye Clinic, National Rehabilitation Center Hospital for the Disabled, Tokorozawa, Japan. 3. Handaya Company, Ltd., Tokyo, Japan.