Ultrasonic biomicroscope-guided radiofrequency ablation of the ciliary body in a rabbit glaucoma model

Destruction of the ciliary body is regarded as a potential way to lower intraocular pressure (IOP) and treat glaucoma patients. This study evaluated the IOP-lowering capability of a novel device for ciliary body radiofrequency ablation (RFA) in a rabbit glaucoma model. The mechanism of RFA-induced IOP reduction was also investigated by evaluating its histological effects. Thirty rabbits were equally divided into the model (n = 10: silicone oil injected eyes), sham (n = 10: silicone oil injected eyes in which sham RFA was performed), and RFA (n = 10: silicone oil injected eyes in which RFA was performed) groups. The glaucoma model was established by injecting silicone oil into the anterior chamber of the rabbit's eye. The temperature of the ablation point in the ciliary body during RFA was recorded using an infrared thermal imager, and the changes in IOP after surgery were compared among groups. The rabbits were monitored for postoperative complications, and histological examinations were performed at 1 week, 1 month, and 6 months after surgery. The success rate of the rabbit eye glaucoma model was 86.7%. Modeling induced an approximately 2.24-fold increase in IOP (from 13.67 ± 1.68 to 30.73 ± 7.68 mmHg) within 1 week. Compared with that in the sham group, the IOP in the RFA group decreased significantly at all follow-up time points (P < 0.01). The overall IOP amplitude decreased by approximately 50%, with the final IOP maintained at approximately 11 mmHg. During RFA, the ablation point temperature increased to 62.53 ± 5.05 ℃. Ultrasonic biomicroscopy after RFA showed ciliary body tissue defects at the ablation site. The ciliary processes were reduced in number, sparsely arranged, and irregularly shaped. Hematoxylin and eosin staining revealed coagulative necrosis of the ciliary processes in the ablation zone, and the bilaminar cells on the ciliary process surface were replaced by dimorphic and dysfunctional non-bilaminar epithelium. Scanning electron microscopy and transmission electron microscopy showed loss of epithelial cells, and the cytoplasm contained fewer mitochondria, which were swollen. The nucleus and chromatin were condensed, indicating cell death and apoptosis. A TdT-mediated dUTP nick-end labeling assay confirmed apoptosis of some epithelial cells. Ciliary body RFA appears to be a feasible, effective, and well-tolerated method of lowering IOP in the rabbit glaucoma model.