Diurnal Variation in Central Corneal Curvature

Various changes in central corneal curvature have been reported. One possible reason for these apparent changes is diurnal variation. After testing the ability of the average clinician accurately and repeatedly to make keratometric readings, we sought to determine if diurnal variation of the corneal curvature does occur. We found that the cornea changed from its flattest curvature in the early morning to its steepest curvature in the early evening.