A novel method to measure oxygen permeability and transmissibility of contact lenses

PURPOSE: The present paper describes an accurate and cost-effective method requiring simple equipment to measure the oxygen permeability and transmissibility of contact lenses. METHOD: The method involves accurate measurement of oxygen across the material by allowing the gas (oxygen) to pass through the lens material in a specially fabricated lens mould. The expelled gas is collected by dissolution in ethanol and the oxygen is measured by titration of the solvent. RESULT: This method is suitable for the measurement of oxygen permeability and transmissibility of contact lenses of varying thickness and different radii of curvature. It can measure Dk and Dk/t of collagen bandage lenses in both wet and dry conditions. CONCLUSION: The oxygen permeability and transmissibility values obtained by this method were compared with the oxygen permeability standard values of commercially available contact lenses and the results are summarised.