CO2 laser-assisted sclerectomy surgery part I: concept and experimental models.

PURPOSE To evaluate the safety and performance of a second-generation device for CO2 laser-assisted sclerectomy surgery system in experimental models. MATERIALS AND METHODS Laser-assisted deep sclerectomy using a modified CO2 laser system (OT-134-"IOPtiMate"; IOPtima Ltd, Israel) was performed in 3 experimental models: enucleated pig eyes, human cadaver eyes, and live rabbit eyes. A half-thickness scleral flap was created, and a CO2 laser with a beam-manipulating system was used to achieve deep scleral ablation over the Schlemm canal zone. Aqueous percolation and scleral perforation rates were recorded. Intraocular pressure was monitored in live rabbits up to 21 days postoperatively. The shape and location of the scleral ablation zone, thermal damage, and the healing process were examined by histopathological analysis. RESULTS Deep scleral ablation and aqueous percolation were repeatedly achieved in all the models. Micro-perforations occurred in 4/18 human eyes (22.2%), in 4/23 rabbit eyes (17.4%), and in none of the 38 porcine eyes. Mean intraocular pressure in the rabbits was significantly decreased (by 6.3±3.6 mm Hg) on the first postoperative day (P<0.0001) and gradually returned to normal. In all but one of the cadaver eyes, effective fluid percolation was achieved. Histology in each case disclosed deep scleral craters with a thin intact sclero-corneal tissue layer at the ablation area. Mild thermal damage, limited to the ablated scleral walls was detected and resolved after 10 days. CONCLUSIONS The results in these experimental studies indicated that CO2 laser-assisted sclerectomy surgery using the OT-134 system is a safe and efficacious procedure for achieving effective fluid percolation.