Optical pachometry measurements: reliability and variability

Polymethyl methacrylate (PMMA) lenses of known thickness were measured by one investigator with a pachometer. This experienced pachometrist held variation in thickness measurements to within 1% over time. The measurements were repeatable with a SD less than 1%. The data indicate that measured corneal thickness changes should be greater than 1 to 2% to be considered true changes in thickness.