INTRAOPERATIVE PACHOMETRY DURING AUTOMATED LAMELLAR KERATOPLASTY - A PRELIMINARY-REPORT

BACKGROUND: The hinge technique greatly improves the results of automa ted lamellar keratoplasty but makes it impossible to measure the thick ness of the corneal cap with a micrometer. We developed a technique of measuring cap and stromal disc thickness with a pachometer and compar ed the results with those obtained with a micrometer. METHODS: Measure ments of the thickness of the stromal disc and/or corneal cap were tak en with the Mitutoyo micrometer and the Chiron Corneo-Gage System III pachometer in five myopic and three hyperopic cases undergoing automat ed lamellar keratoplasty with complete cap resection. The intended pos toperative refraction was plano. Postoperative refractions were taken at two months. RESULTS: In most cases, the corneal cap measured thinne r while the stromal disc measured thicker by the micrometer than by th e pachometer because of the hydration status of the stromal bed. In bo th myopic and hyperopic cases, the thickness measurements taken with t he pachometer correlated better with the postoperative spherical equiv alent values than those taken with the micrometer. CONCLUSIONS: The th ickness measurement of corneal resections by both micrometry and pacho metry is greatly influenced by tissue hydration status. When hydration is similar, the pachometer provides more accurate thickness readings than does the micrometer, as determined by correlations with intended refractive results.