A novel method to quantify the edge contour of RGP contact lenses

A new method of accurate profile measurement of rigid gas permeable lenses and edges is described. A purpose built optical profilometer non-destructively scans complete cross-sections in several meridians of any rigid lens. The accuracy of the instrument was verified to be better than +/-2.5 microm. The profile data are obtained and stored in digital format for further analysis. The seven most commonly used edge features were defined by means of mathematical algorithms to extract unique numerical values for these parameters from the measured profiles. Applications of the new edge quantification method in clinical contact lens research and manufacturing quality control are shown.