CO₂, Excimer and Erbium:YAG Laser in Deep Sclerectomy

<i>Purpose:</i> Deep sclerectomy is a non-penetrating filtering procedure that is not generally accepted, as tissue dissection is difficult and varying success rates have been reported. The purpose of the present study was to compare the use of CO₂, excimer and erbium:YAG lasers in dissection of the deep corneoscleral lamella. <i>Methods:</i> In enucleated porcine eyes a superficial lamellar scleral flap of 5 × 5 mm was surgically dissected. The deep lamella was removed using a pulsed erbium:YAG, a CO₂ or an excimer laser (10 eyes/group). All eyes were analysed histologically and 3 in each group by scanning electron microscopy (SEM). <i>Results:</i> It is feasible to ablate the deep corneoscleral lamella with the CO₂, excimer and erbium:YAG lasers without perforating the anterior chamber. The following histology and SEM showed a smoother surface after dissection with the CO₂ and excimer lasers compared to the erbium:YAG laser. There was no thermal damage after excimer laser treatment, compared to a damage zone of 10–30 µm using the erbium laser and one of 70–100 µm with the CO₂ laser. <i>Conclusions:</i> Excimer,erbium:YAG and CO₂ lasers allow the microsurgical dissection of the deep lamella. The excimer and CO₂ lasers achieve a more regular and smoother tissue surface. The excimer laser has the advantage to dissect without thermal tissue damage.