Corneal Pachymetry Prior to Radial Keratotomy: A Comparison of Techniques

Abstract

Central corneal thickness was measured by ultrasound in the clinic and compared with the intraoperative measurement. The central corneal pachymetry readings were not significantly different (p>0.05). Preoperative mapping of corneal thickness may therefore be satisfactory prior to refractive surgery. Three different techniques of pachymetry were also compared: optical, specular microscope, and ultrasonic. Specular microscope and optical measurements were not significantly different; however, these two techniques differed significantly (p<0.001) from ultrasound, with ultrasound measuring an average of 0.01 mm thinner. A significant right/left difference in corneal thickness was found only with the specular microscope (p<0,01), with the left eye measuring an average 0.01 mm thinner than the right. Only the ultrasonic pachymeter allowed convenient mapping of corneal thickness outside the central corneal zone.