Sight Sciences, Inc recently introduced the Sion Surgical Instrument to meet physicians’ desire for an efficient and easy-to-navigate bladeless goniotomy. Arkadiy Yadgarov, MD, a glaucoma and cataract surgeon at Omni Eye of Atlanta, who was the first surgeon to use the Sion Surgical Instrument in human eyes with glaucoma, says, “Anything sharp that enters the eye has greater potential to cause harm. If I can perform the same goniotomy without a sharp tip, then that makes more sense.”

Dr. Yadgarov was also impressed that the Sion can grab onto excised trabecular meshwork (TM) and cleave the strip off the canal, allowing it to be removed from the eye. In his experience, no large trabecular leaflets have been left behind.

How It Works

The Sion Surgical Instrument is a sterile, single use, manually operated device used in ophthalmic surgical procedures to excise TM. The tip of the Sion instrument contains an “upper foot” control window to enable visibility of the unroofing process as well as a “lower foot” for ease of placement and controlled movement. Designed to remove multiple clock hours of diseased TM, the tip is inserted into the eye through a pre-existing clear corneal incision at least 2 mm wide. From there, the TM is identified under gonioscopic visualization. Using the rounded “toe” of the lower foot, the tip of Sion is advanced into Schlemm’s canal.

The lower foot’s stainless-steel skid allows for ease of placement, coming to a rest against the scleral wall. Nestled into position, the device’s upper foot will find itself resting atop the TM. From there, the instrument is advanced, with the heel of the lower foot acting as an anchor against the back wall, ensuring smooth movement throughout the goniotomy.

Additionally, the upper foot’s tissue collection window provides visibility throughout the procedure. Sion’s bladeless design lifts and gathers the TM. As it travels, the mouth of the device collects the meshwork in folds. Once advancement is complete, the Sion instrument’s movement is reversed back to the initial area of contact. When complete, the Sion instrument can be removed from the eye. Residual TM may be removed with microforceps or aspiration.

Larissa Camejo, MD, glaucoma specialist and CEO and founder of Larissa Camejo MD in Palm Beach Gardens, Florida, who provided insight during the product’s development and was one of the first surgeons to use Sion, says after removing TM with the Sion, it is collected between 2 plates that act as a trap. This provides direct access to Schlemm’s canal and the rest of the conventional outflow pathway. The instrument can be used in a forehanded or backhanded fashion to remove the desired clock hours of TM.

Product Benefits

The Sion is ergonomic, lightweight, and comfortable to use, Dr. Camejo says. “It moves in a nonresistant fashion and advances smoothly throughout the procedure,” she says. “Due to its small size, it’s easy to manipulate intraocularly and allows for easy visibility.”

Dr. Yadgarov stated that a benefit of a bladeless design is that it may reduce unintentional damage to other tissues of the eye. During goniotomies, various scenarios such as eye movement or tip slippage can occur, causing the goniotomy device tip to hit the iris root or ciliary body. If the tip is sharp, there is more potential for harm and bleeding, or even disinsertion of ocular tissues. A blunt tip would be less traumatic in these instances, which may reduce the potential for bleeding and cuts to ocular tissues.

Clinical Applications

Dr. Yadgarov performs goniotomy in eyes with heavy trabecular pigmentation in which removing TM and its leaflets may provide more benefits over stenting procedures. He also prefers to perform goniotomy over stenting in eyes with any corneal guttata. Dr. Camejo says goniotomy is a procedure that can be performed in specific phakic or pseudophakic patients as well as combined with cataract surgery.

Improving Patient Outcomes

According to Dr. Yadgarov, “There is robust literature^1,2 that excisional goniotomy procedures work well for glaucoma patients. The Sion device improves the efficiency of the procedure, which I believe will increase adoption of a bladeless approach to goniotomy.”

Dr. Camejo says, “What matters the most is what happens in real life. My initial experience with Sion is that it helps to perform goniotomy really well. I’m excited to see the long-term results.” GP

References

1. Dickerson JE Jr, Brown RH. Circumferential canal surgery: a brief history. Curr Opin Ophthalmol. 2020;31(2):139-146. doi:10.1097/ICU.0000000000000639
2. Ahuja Y, Ma Khin Pyi S, Malihi M, Hodge DO, Sit AJ. Clinical results of ab interno trabeculotomy using the trabectome for open-angle glaucoma: the Mayo Clinic series in Rochester, Minnesota. Am J Ophthalmol. 2013;156(5):927-935.e2. doi:10.1016/j.ajo.2013.06.001