Purpose:
To study the effects of ultrasonic cyclocoagulation on the surface of the ciliary body and adjacent structures in rabbit eyes.
Methods:
Four eyes of 4 rabbits were insonified with a ring-shaped probe containing 6 miniaturized high-intensity focused ultrasound transducers operating at 21 MHz. The acoustic power was set at 2 W, and the exposure duration at 4 sec per transducer. Macroscopic examinations and intraocular pressure measurements (IOP) were performed before the treatment, and 1 and 4 days after. Histological examinations of the enucleated eyes were performed with scanning electron microscopy.
Results:
IOP was reduced from a mean preoperative value of 10.1 ± 2.4 mmHg before treatment to a mean postoperative value of 7.8 ± 1.3 mmHg and 6.3 ± 2 mmHg at 1 and 4 days. No macroscopic abnormalities were found. In the affected regions, histological examinations demonstrated a complete loss of the bi-layered ciliary epithelium, showing a smooth basal membrane (Figure 1, left). Ciliary processes appeared bulky probably because of stromal edema. In the unaffected regions, histological examinations showed epithelial cells covering the ciliary processes (Figure 1, right). The other structures appeared undamaged.
Conclusions:
Ultrasonic cyclocoagulation of the ciliary body using high-intensity focused ultrasound results in histologic loss of the bi-layered ciliary epithelium, likely resulting in decrease of aqueous production.