This International Standard, together with ISO 15004-1, specifies requirements and test methods for continuously or digitally indicating ophthalmometers. Certain types of ophthalmometer (designated as code 1 in Table 1) are capable of measuring radii of curvature of contact lenses as described in ISO 18369-3:2006, 4.1. It is assumed that the local corneal front surface and both contact lens surfaces are spherical or toroidal. This International Standard takes priority over ISO 15004-1, if differences exist.