Introduction Within the last decade, the corneal contact lens has evolved from an optical curiosity into a widely accepted visual aid. The manufacturing and fitting techniques have become an exacting science. However, expedient clinical methods for the measurement and evaluation of the corneal curvatures have significantly lagged behind those of lens production and modification. The use of standard instruments to measure the radius of curvature of the cornea ordinarily requires that the patient sight a fixed target, either a mirrored image of the eye itself or some form of stationary fixation object, while the keratometric reading is made.* In the majority of normal eyes this method is satisfactory. There are, however, a number of normal as well as many abnormal conditions in which this technique will not always produce so-calledtruemeasurements. These conditions may be unusually high astigmatism, keratoconus, or the result of cataract extraction, keratoplasty, pterygium resection, or