Impedance of a goat eye lens

The complex electrical impedance of a goat eye lens is studied in the frequency range 10mHz−10Hz at room temperature, using a computer-controlled AC impedance system. AC impedance software (model 368, version 2.2) is employed to determine the total impedance and capacitance of the eye lens at various frequencies. A Cole-Cole plot of the eye lens material is drawn between the real component of impedance Z′ and the imaginary component Z″ for each excitation frequency that shows a perfect arc of a semicircle, with its centre lying below the abscissa at an angle of 35°. The half-angle ϕ between R0 and R∞ is found to be 55°, which mathematically demonstrates the selective permeability of the eye lens. Using graphical analysis of the Cole-Cole plot, characteristic frequency fc and distribution factor α are observed to be 1Hz and 0.77, respectively. At characteristic frequency, capacitance and total impedance are found to be 1.14μF and 9.08kΩ. The effect of electrode polarisation on capacitance is corrected, based on Fricke's power function. The observed electrical parameters are then used to explain the multiple current path through various tissue compartments. Further, an attempt is made to explain the results on the basis of a possible dipolar model.