Eyeworld

EW FEATURE 50 Facing complicated glaucoma cases • February 2019 AT A GLANCE • Using viscoelastic in glaucoma surgery can be a tool to help maintain space in the anterior chamber and minimize the chance of having low pressure. • Viscoelastic can be used in traditional glaucoma surgeries as well as in MIGS. • Dispersive and cohesive viscoelas- tics have different roles in glaucoma surgery, with dispersives being particularly helpful in tamponading bleeding. by Ellen Stodola EyeWorld Senior Staff Writer/Digital Editor said that he tends to leave some of it behind, especially if he has done an Ahmed valve or a tube to prevent the eye pressure from going too low. Dr. Noecker added that he uses both cohesive and dispersive vis- coelastic but tends to use cohesive more. When you are doing MIGS and need to visualize the angle, he thinks the dispersive viscoelastics are a little better at maintaining space and staying in the eye. Jacob Brubaker, MD, Sacra- mento, California, agreed, saying that he thinks cohesive viscoelastic has a "bigger niche in the glaucoma world." He uses Healon in the anterior chamber when doing a trabeculec- tomy to maintain the chamber. Dr. Brubaker added that once he's sutured the flaps, he can evacuate the viscoelastic out of the eye. He generally does not leave viscoelastic in the eye after a trabeculectomy. Healon is good because once you repressurize the eye, the viscoelastic comes out easily, he said. Dr. Brubaker added the disper- sive viscoelastic is good for coating the endothelium of the cornea, which is helpful for cataract surgery. He uses Viscoat (sodium chondroi- tin sulfate/sodium hyaluronate, Alcon) at the beginning of cataract surgeries. have the highest risk of hypotony or low pressure, he said. During surgery, viscoelastic helps maintain space and keeps the eye from collapsing, which could be catastrophic and cause a supracho- roidal hemorrhage if the pressure is too low, Dr. Noecker said. The viscoelastic helps "firm up" the eye and make space when in- serting it. "In those surgeries, I also leave it in the eye to keep pressure from going too low," Dr. Noecker said. He tends to use Healon (sodi- um hyaluronate, Johnson & John- son Vision, Santa Ana, California) in these cases, and it will slowly filter out of the eye over a couple of days. The viscoelastic allows for aqueous to flow through, he said, so as long as you have an opening working properly, there's not a problem. Dr. Noecker also uses viscoelas- tic in tube shunts, where he puts it in to begin the case. He likes to put tubes into the sulcus and behind the iris. If the patient still has the nat- ural lens, Dr. Noecker said he uses it to inflate the angle to make space and keep the eye pressurized during the surgery. If you want to put the tube behind the sulcus, the visco- elastic inflates that space, he said. It can push the iris forward and the lens implant backward. Dr. Noecker pletely filling the anterior chamber with cohesive viscoelastic," he said, adding that he uses ProVisc (sodium hyaluronate, Alcon, Fort Worth, Texas). "You can leave the anterior chamber packed full after an Ahmed valve and you won't get a pressure spike," Dr. Radcliffe said. You don't need to remove the viscoelastic, as it will get filtered out through the valve. "Ironically, filling the eye with a cohesive viscoelastic and placing the patient on oral acetazol- amide after Ahmed valve placement can result in a deep chamber that will stay deep for the first few days following surgery, since presumably aqueous production is required to force the viscoelastic to leave the anterior chamber," he said. Dr. Radcliffe noted that since he's adopted the use of viscoelastic in his practice, the need to take patients back to the operating room for procedures such as drain choroi- dal effusions—a complication when pressure is too low for too long and the choroid swells—has been eliminated. Meanwhile, Robert Noecker, MD, Fairfield, Connecticut, said that he uses viscoelastics during traditional glaucoma surgery, such as trabeculectomy or EX-PRESS Glaucoma Filtration Device (Alcon), to pressurize the eye. Those surgeries Though traditionally used in cataract surgery, viscoelastics are also useful in glaucoma surgery T he use of OVD has evolved from its place in cataract surgery to being useful in glaucoma surgery. Nathan Radcliffe, MD, New York, noted that though he finds visco- elastics to be used frequently in glaucoma surgery, there is not a lot of research or published literature on this. Furthermore, he noted that the on-label use of viscoelastics is for placement in the eye during intraoc- ular surgery (to be removed entirely following the procedure). He added that though viscoelastic use in glau- coma surgery is technically off-la- bel, it can help reform the anterior chamber of the eye if intraocular pressure is low, can tamponade bleeding, and can help prevent low intraocular pressure or hypotony. How to routinely use OVDs in traditional glaucoma surgery Dr. Radcliffe first began using visco- elastics in glaucoma surgery when he started implanting the Ahmed Glaucoma Valve (New World Medi- cal, Rancho Cucamonga, California) as a young surgeon. The Ahmed valve has its own intrinsic way of resisting fluid outflow, he said, and the valve is designed to set the pres- sure to 5 or 6 mm Hg early on in the healing process. However, he found that if you remove all viscoelastic after cataract surgery, the pressure can often be too low in the early postoperative period. "I began com- Using OVDs in glaucoma surgery Slit lamp photograph of an anterior chamber filled with a cohesive viscoelastic after Ahmed valve placement. There is suspended blood in the anterior chamber. Source: Nathan Radcliffe, MD

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