The accuracy of ultrasonic determination of axial length in pseudophakic eyes.

The axial length was calculated by refractive means in 206 pseudophakic eyes and compared with the axial length measured by ultrasound using a Kretz 7200 MA A-scanner or a Sonometrics DBR 400 scanner. The difference (+/- SD) between the calculated and the measured axial length was 0.13 mm (+/- 0.54) and 0.08 mm (+/- 0.28) using the Kretz and Sonometrics equipment, respectively (P less than 0.01). The lower variation between the calculated and the measured axial length observed with the Sonometrics scanner indicated this instrument to be the most accurate. The calculated axial length may be used in future studies on the clinical accuracy of ultrasonic equipment.