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CO2 laser-assisted sclerectomy may benefit some cases of medically uncontrolled glaucoma
Most patients maintained a reduction in IOP at 12 months. Complications were mild and transitory.
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Patients with medically uncontrolled primary open-angle glaucoma or pseudoexfoliative glaucoma may benefit from CO2 laser-assisted sclerectomy surgery.
The high-tech procedure is also an attractive alternative to manual nonpenetrating deep sclerectomy, a study found.
“Although CO2 laser is very effective in ablating dry material, it is almost completely absorbed by water; therefore, it is not practical for intraocular use,” study co-author Ehud I. Assia, MD, told Ocular Surgery News.
Dr. Assia and colleagues postulated that these special characteristics of the CO2 laser might be advantageous for nonpenetrating glaucoma surgery.
“Ablation of the dry sclera over the drainage system results in controlled thinning of the tissue and unroofing of the trabecular meshwork and Schlemm’s canal, until fluid effectively percolates,” Dr. Assia said. “Additional laser applications are absorbed by the outcoming fluid, and the laser effect ceases at the desired endpoint, namely, effective fluid percolation.”
The study
Thirty-seven patients with either primary open-angle glaucoma or pseudoexfoliative glaucoma underwent CO2 laser-assisted sclerectomy surgery (CLASS) with the CO2 laser system OT-134-IOPtiMate (IOPtima); 30 of the patients completed 12 months of follow-up.
Ehud I. Assia
The mean baseline IOP was 26.3 mm Hg, which decreased to 14.4 mm Hg at 6 months and 14.3 mm Hg at 12 months.
Complete success at 6 months and 12 months was defined as IOP ranging from 5 mm Hg to 18 mm Hg, as well as IOP reduction greater than 20% of baseline, without the need for additional medication or filtration surgery. Overall, 76.7% reached this goal at 6 months and 60% at 12 months.
Success was qualified, meaning patients required hypotensive medications postoperatively, in 83.3% of patients at 6 months and in 86.6% of patients at 12 months.
“Usually, the pressure the day after surgery is quite low — typically at a level of 5 mm Hg to 7 mm Hg — yet the anterior chamber is deep and stable,” Dr. Assia, the inventor of the laser technology and an OSN Europe Edition Board Member, said. “The eye is normally quiet, and vision is maintained soon after surgery.”
The prospective study, published in the Journal of Glaucoma, was conducted at five centers worldwide.
Additionally, no laser-related complications were recorded. All mild transitory complications resolved spontaneously or with conservative treatment by 1 month after surgery; these included four cases of superficial punctuate keratitis, one case each of microhyphema, infectious conjunctivitis and wound dehiscence, and two cases of wound leak.
“The main advantage of nonpenetrating filtration surgery is its safety profile, [because] it is practically an extraocular surgery. The risk of hypotony, hyphema, shallow chamber, etc., is significantly reduced,” Dr. Assia said. “However, this surgery demands high skills, considerable experience and is time-consuming. CLASS accomplishes the same in a controlled manner in a much shorter time, and the learning curve is fast. The fluid percolation is titrated during surgery, and further laser applications are provided until a satisfactory clinical result is achieved.”
Longer follow-up
Since the study was submitted for publication, the authors have completed a series of 51 patients with CLASS, for which IOP dropped from a mean of 26.3 mm Hg to 14.3 mm Hg at 1 year and to 14.6 mm Hg in 16 patients at 2 years, Dr. Assia said.
“IOP lower than 18 mm Hg was achieved in 87% of the eyes at 1 year,” he said.
To increase the efficacy of CLASS, Dr. Assia said that a wide exposure of the sclera is probably more effective than a small flap and that ablation should not be stopped before effective percolation is attained.
In the worst case, perforation may occur, and surgery can then be converted to a routine trabeculectomy.
“Application of mitomycin C with CLASS is also recommended, and the role of spacers under the flap should be studied,” Dr. Assia said. – by Bob Kronemyer
Reference:
- Geffen N, Ton Y, Degani J, Assia EI. CO2 laser-assisted sclerectomy surgery, part II: multicenter clinical preliminary study.J Glaucoma. 2012;21(3):193-198.
For more information:
- Ehud I. Assia, MD, can be reached at Department of Ophthalmology, Meir Medical Center, 59 Tchernichovsky St., 44281 Kfar-Saba, Israel; +972-9-7472511/1527; email: assia@netvision.net.il.
- Disclosure: Dr. Assia is the inventor of the laser technology and owns shares of IOPtima.