This part of ISO 18369 specifies the methods for measuring the physical and optical properties of contact lenses specified in ISO 18369-2, i.e. radius of curvature, back vertex power, diameter, thickness, inspection of edges, inclusions and surface imperfections, and determination of spectral transmittance. This part of ISO 18369 also specifies the equilibrating solution, standard saline solution, for testing of contact lenses.