Wide-Field Oxygen Permeability Measurement of Contact Lenses Using a Modified Polarographic Electrode Cell

Oxygen permeability (Dk) is a key parameter for evaluating the ability of contact lenses to supply oxygen to the cornea. Although the polarographic method has been standardized as a reference technique for Dk measurement, conventional polarographic electrode cells are limited to a narrow central measurement area of approximately 4 mm in diameter, which may not adequately represent oxygen transport under actual wearing conditions. In this study, a modified polarographic electrode cell enabling wide-field oxygen permeability measurement over an expanded central area with a diameter of 11 mm was developed and evaluated under ISO 18369 measurement conditions. The performance of the proposed system was evaluated by comparing its accuracy, repeatability, and relative error with those of a conventional polarographic electrode cell using plano hydrogel contact lens samples with different uniform thicknesses. The Dk values obtained using the modified measurement cell did not show a statistically significant difference compared to those measured with the conventional measurement cell (t = 2.682, p = 0.055), and the relative error between the two systems was 1.93%, meeting the ISO acceptance criteria for the development of a new testing method. These results demonstrate that wide-field Dk measurement can be achieved without compromising reliability, providing a more representative and ISO-compliant approach for contact lens oxygen permeability evaluation.