How use of a shunt device may augment deep sclerectomy

Montreal-Deep sclerectomy augmented with implantation of a gold mini-shunt (Gold Mini Shunt Plus, SOLX) in the suprachoroidal space is a safe and effective technique for lowering IOP in eyes with moderate to advanced open-angle glaucoma, according to findings from researchers at the University of Montreal.

(Video courtesy of Paul Harasymowycz, MD)

Paul Harasymowycz, MD, assistant professor and chief of the glaucoma service, was motivated to develop the combined procedure after finding increased scarring in eyes implanted with the third generation of the device. Reasoning that the scarring was the result of a high aqueous flow rate through the device, which has all ingress holes open, he surmised that the trabeculoDescemet window of the deep sclerectomy could help to control aqueous flow, limiting it initially but yet providing a means to increase it through use of YAG laser puncture if further IOP-lowering was needed.

In addition, Dr. Harasymowycz believed that corneal irritation and formation of membranes obstructing the shunt’s holes would be avoided with this combined technique in which the shunt does not go into the anterior chamber.

Samuel Levallois, MD, ophthalmology resident, highlighted results from a retrospective review of 1-year outcomes in 20 eyes (16 patients) that underwent the combined procedure. Mitomycin-C (0.5 mg/ml for 1 min) was used in all cases, and some eyes also had cataract surgery.

Mean IOP decreased from 35.7 mm Hg preoperatively to 15.9 mm Hg, and mean daily medication use decreased from 3.4 to 1.8. In an analysis excluding three eyes with previous incisional glaucoma surgery, mean IOP at 1 year was 15 mm Hg and mean daily medication use was 0.8.

Nearly half of the eyes underwent goniopuncture at an average of 6 weeks postoperatively, a rate typical for nonpenetrating glaucoma procedures, and bleb needling with an anti-vascular endothelial growth factor agent was performed to reduce the risk of scarring in three eyes with aggressive wound healing. No eyes developed choroidal detachment, hyphema, uveitis, or corneal edema, or corneal opacification.

“We believe these are very good results,” Dr. Harasymomycz said. “However, we recognize it would be ideal to conduct a randomized study comparing use of the gold shunt and deep sclerectomy with a standard nonpenetrating technique.

He also commented on the use of mitomycin-C, noting that some surgeons feel uncomfortable about applying the antimetabolite when making a full thickness incision into the suprachoroidal space.

“Although surgeons raise concern about potential choroidal toxicity, I believe it is advantageous to use an antimetabolite,” he explained. “Most studies looking at techniques that enhance suprachoroidal flow show that there are fibroblasts that can potentially cause scarring and therefore lead to increased IOP.”

Dr. Harasymowycz is a consultant for SOLX. This article was adapted from Dr. Levallois’ presentation during the 2013 meeting of the American Society of Cataract and Refractive Surgery.

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