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CO2 laser-assisted sclerectomy reduces IOP, medication use
Laser energy is applied with a brief exposure time, resulting in little scarring and inflammation.
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Carbon dioxide laser-assisted sclerectomy reduced IOP and medication use in patients with open-angle glaucoma, according to a poster presented at the European Glaucoma Society meeting.
Mauricio Turati, MD, Félix Gil-Carrasco, MD, and colleagues described outcomes achieved with CO2 laser- assisted sclerectomy (CLASS).
“The advantage of this technique, compared with the conventional manual technique of nonpenetrating deep sclerectomy, is that the learning curve with the laser is very short,” Turati said in an interview with Ocular Surgery News. “You only have to do one or two surgeries so you can have the experience to keep doing more surgeries with patients.”
The CLASS procedure involves the creation of conjunctival and scleral flaps and does not require entry into the anterior chamber. Tissue ablation facilitates the percolation of fluid through the inner wall of Schlemm’s canal.
“You don’t have a shallow or flat anterior chamber. There is much less inflammation [compared with conventional trabeculectomy],” he said.
“[The laser] applies a high and localized energy in a very short period of time, which allows the tissue to be ablated without doing any harm, especially with the heat, to the adjacent tissues,” he said.
Flap creation and tissue ablation
The CLASS procedure is performed with a CO2 laser combined with the IOPtiMate system (OT-134-IOPtiMate, IOPtima).
The procedure involves manually opening the conjunctiva to expose the sclera, Turati said.
“We prepare to do a fornix-based flap because the scarring is better,” he said. “The scarring line forms at the limbus and leaves the conjunctiva … at the posterior part so that the fluid that is coming out of the eye can go to the back with no scarring line behind the scleral flap.”
CLASS procedure – laser ablation aimed at Schlemm’s canal.
Image:IOPtima
The surgeon may apply mitomycin before creating a superficial scleral flap. The scleral flap is extended to the clear cornea.
“You first create a scleral bed. After you create a bed, you start shooting with the laser directly over where Schlemm’s canal should be,” Turati said. “You have to keep shooting with the laser until you start to see Schlemm’s channel. You see how the liquid percolates, and you see how you start getting flow from inside the eye to outside the eye. At that point, you have created enough ablation to ‘unroof’ the scleral channel.”
IOPtima specified that the laser should be positioned under the limbus line. They also stated that because CO2 laser energy is absorbed and blocked by nature in liquid, once percolation finds place, the laser does not penetrate further into the eye.
The surgeon uses loose sutures to close the scleral flap, Turati said, and tight sutures to close the conjunctival flap.
“If you decided not to use mitomycin, at the end of the procedure, once you have closed the conjunctiva, you can inject subconjunctival bevacizumab, so you can also reduce scarring and promote the success of the surgery,” he said.
Three-year study results
The poster outlined a study that included 13 patients with primary open-angle glaucoma who were eligible for the CLASS procedure; 12 patients completed 1 year of follow-up, nine patients completed 2 years, and eight patients completed 3 years.
Complete success was IOP between 5 mm Hg and 18 mm Hg and a 20% reduction in IOP with no medication at up to 3 years. Qualified success was the same IOP target, with or without medication.
Mean preoperative IOP was 24 mm Hg ± 5.4 mm Hg. Mean postoperative IOP was 14.5 mm Hg ± 3.0 mm Hg at 1 year, 12.8 mm Hg ± 2.3 mm Hg at 2 years and 13.4 mm Hg ± 2.3 mm Hg at 3 years.
Mean preoperative medication use was 3.8 ± 0.7. Mean postoperative medication use was 1.2 ± 1.2 at 1 year and 1.6 ± 0.7 at 2 and 3 years. Subsequent mean medication use was 1.8 ± 0.4 at 4 years and 2 ± 0.0 at 5 years.
The qualified success rate was 92.3% at 1 year, 90% at 2 years and 88.9% at 3 years. The complete success rate was 38.5% at 1 year, 10% at 2 years and 11.1% at 3 years.
“Visual acuity remains practically unchanged from day 1 of the surgery,” Turati said.
There were a few mild complications in the early postoperative period that resolved with no sequelae. – by Matt Hasson