We used a corneal topography analysis system to evaluate nine eyes of seven patients in whom the diagnosis of keratoconus was suspected. There was no slit-lamp evidence of the condition. In seven of nine eyes a cone was identified. Large amounts of corneal distortion were seen in selected patients even though they had excellent spectacle-corrected visual acuity and little or no distortion of the keratometer mires. These findings suggest that corneal topography analysis systems are useful in the detection and description of corneal irregularity in the early stages of keratoconus. The radial keratotomy surgeon should be aware that normal results on slit-lamp examination and normal keratometry and refractive data do not rule out the presence of early keratoconus.