It was absolutely mandatory to establish an exact profile of corneal sensitivity in order to appreciate the results of clinical measurements. Only this would allow us to evaluate clinical problems of threshold changes. We therefore measured the corneal sensitivity at thirteen different areas of 20 to 40 year-old subjects. The measurements were taken on four meridians, at the limbus, 1 mm from the limbus, at a point between the center and this area, and at the center. These thresholds can be plotted as a characteristic profile (Fig. 32).