Thickness of human cornea measured by topographic pachometry.

In the hands of trained user, the topographic pachometer proves to be an instrument of acceptable clinical precision (standard deviation = 0.006mm). An examination of corneal thinning during waking hours revealed a rate of thinning which was greatest upon lid opening and which declined uniformly throughout the day (p = 0.01). An investigation into menstrually related change in corneal thickness revealed that at least 122 subjects would be required to investigate this change on an acceptable statistical basis (p = 0.05).