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

Area of Science:

• Ophthalmic optics
• Biomaterials science
• Measurement science

Background:

• Oxygen permeability (Dk) is crucial for contact lens performance.
• Conventional Dk measurement methods have limited central measurement areas.
• This limitation may not reflect real-world oxygen transport under lens wear.

Purpose of the Study:

• To develop and evaluate a modified polarographic electrode cell for wide-field Dk measurement.
• To assess if expanded measurement area (11 mm diameter) improves representativeness.
• To ensure the new method meets ISO 18369 standards.

Main Methods:

• Developed a modified polarographic electrode cell for wide-field Dk measurement.
• Evaluated the system using plano hydrogel contact lenses of varying thicknesses.
• Compared accuracy, repeatability, and relative error against a conventional cell under ISO 18369 conditions.

Main Results:

• The modified cell achieved a wide-field measurement area of 11 mm.
• No statistically significant difference in Dk values was found compared to the conventional cell (p = 0.055).
• Relative error was 1.93%, meeting ISO acceptance criteria.

Conclusions:

• Wide-field Dk measurement is achievable without compromising reliability.
• The developed method offers a more representative evaluation of contact lens oxygen permeability.
• This approach is ISO-compliant and suitable for new testing method development.