[Damage to cultured corneal endothelium caused by ultrasound during phacoemulsification]

An experimental study was performed to estimate the degree of corneal endothelial damage caused by ultrasound during phacoemulsification. Cultured corneal endothelium prepared from bovine eyes was exposed to ultrasound. Dead cell rates were determined by counting the number of cells positively stained by trypan blue under various conditions of ultrasonic radiation. Dead cell rate increased from 13 +/- 2% to 39 +/- 4% (n = 5, Mean +/- S.D.) as ultrasonic duration was prolonged from 15 seconds to 45 seconds. Dead cell rate increased from 6 +/- 1% to 39 +/- 4% as ultrasonic power increased from 60% to 100%. Dead cell rate increased from 8 +/- 1% to 44 +/- 11% as the distance of the phaco tip decreased from 7 mm to 4 mm. Dead cell rate increased from 4 +/- 2% to 35 +/- 7% as the angle of the phaco tip increased from 30 degrees to 90 degrees. We confirmed that endothelial damage depended on ultrasonic duration, ultrasonic power, the distance of the phaco tip, and the angle of the phaco tip. We suggest that the endothelium is damaged mainly by shock waves emanating from the phaco tip.