Measurement of impedance in vivo in eye lids-development of examination of malignant lid tumors

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Dr.Makio Watanabe (head investigator,2002,2003) has investigated measurement of impedance in many types of cells and tissues, and has demonstrated that measurement of impedance in vitro in ocular cells and tissues was possible. Next, he succeeded to measure impedance in vivo of cornea of experimental animals. However, it has not been examined to measure corneal impedance in vivo in humans. Therefore, in this study, we aimed to measure impedance in vivo of ocular tissues in humans. First, after obtaining approval of Kochi Medical School Ethical Committee, we tried to measure corneal impedance in vivo in humans, including healthy volunteers and patients with bullous keratopathy. By using the surface electrode and the impedance analyzer 4194A (Hewlett-Packard) under the control of personal computer, impedance of cornea was measured from 10 KHz to 100 MHz. Data demonstrated that the ratio of the dispersions between low frequency and high frequency differed between healthy volunteers and patients with bullous keratopathy. The ratio was around 1.5 in healthy volunteers, while about 0.5 in patients with bullous keratopathy. Furthermore, we found the trend that a correlation existed between the ratio and the number of corneal endothelial cells. Next, we tried to measure impedance of patients with lid tumor. However, although repeated improvements of the surface electrode, we were not able to measure impedance in vivo of patients with lid tumor.