Pupil size in relation to ultrasonic anterior chamber depth measurements in pseudophakic eyes.

The effect of pupil size on ultrasonically determined anterior-chamber depth was studied in vitro with the Storz Alpha 20/20 and with the Kretz ultrasonoscope at high and low system sensitivity. The traces were measured peak to peak and base to base; results were compared to anterior-chamber depth measurements with optical pachymetry. We conclude that when measuring anterior-chamber depth with ultrasound, the pupil must be fully dilated or reduced system sensitivity must be used and the traces measured peak to peak.