Change in the corneal structure. Changes in the cornea as a result of ultrasound application as compared to sham-treated corneas (n = 8). Different bars represent the corneal damage due to ultrasound application at frequencies of 400 kHz (n = 6) and 600 kHz (n = 6). Data are shown as mean ± standard deviation. No changes were observed in control corneas (n = 20) in all cases. *p value <0.05; **p value <0.001.