Eyeworld

92 | EYEWORLD | APRIL 2022 G UCOMA by Liz Hillman Editorial Co-Director About the physicians Daniel Lee, MD Director Glaucoma Research Center Wills Eye Hospital Philadelphia, Pennsylvania Sarah Van Tassel, MD Assistant Professor of Ophthalmology Weill Cornell Medicine New York, New York W hile modern angle surgery has been a boon for patients and physicians wishing to avoid or delay more invasive glaucoma procedures and/or reduce the number of topical medications, cyclodialysis cleft, while rare, is still a complication. Daniel Lee, MD, said this occurs when a de- vice or surgical instrument physically disinserts the ciliary body from the scleral wall during surgery. "Cyclodialysis clefts represent the pinnacle of MIGS-related complications. Even a small cleft can act as an aqueous sink, diverting fluid away from physiologic outflow systems, al- most always resulting in profound hypotony," Dr. Lee said. "Vision is predictably going to be significantly impaired. Cleft closures are often accompanied by dramatic pressure elevations, which are unpredictable in timing and scale. These issues are compounded by heightened patient expectations as MIGS procedures are often described as the lower risk, 'easier,' and less vision-impacting options." Sarah Van Tassel, MD, told EyeWorld that a cyclodialysis cleft can occur any time during angle surgery when anatomy posterior to the trabecular meshwork is engaged with a surgical instrument or MIGS device. "Intuitively, I would expect this most during procedures that involve horizontal or sweeping motion in the angle, but in review of the FDA MAUDE database, 1 my group found that surger- ies like placement of the CyPass device [Alcon, withdrawn from the market], iStent/iStent inject [Glaukos], and XEN Gel Stent [Allergan] can also cause clefts," Dr. Van Tassel said. Dr. Lee said with the popularization of angle-based glaucoma procedures, there is an increased incidence of cyclodialysis cleft, but glaucoma procedures are not the only intraocu- lar surgery that can result in this complication. A paper published decades ago described six cases where patients had hypotony due to inad- vertent cyclodialysis after IOL implantation. 2 Risk factors Dr. Lee said he's seen cyclodialysis cleft arise from all angle-based surgeries, with the rate seeming proportional to the extent and duration of the angle treatment. "Perhaps the most com- mon cause of cyclodialysis cleft is a suboptimal gonioscopic view of the angle during surgery," Dr. Lee said. "This may be due to corneal opac- ities from corneal edema, arcus, prior scarring, etc. Unclear angle anatomy may be another cause. Very lightly pigmented meshwork can challenge landmark identification." Other risk factors for this complication in- clude patients who are not cooperative or who have involuntary tremors, both of which should be noted prior to surgery, Dr. Lee said. Preventative measures Prevention, Dr. Lee said, starts at the preop office visit. He said that gonioscopy can help identify potential pitfalls, such as pale TM, prominent peripheral iris vessels, and blood in Schlemm's canal from elevated episcleral venous pressure. "Patient-related factors that would limit effective communication, such as language bar- riers, cognitive deficits, and poor cooperation, are also factors to consider when determining type of procedure and/or level of anesthesia," he said. With a poor view of the angle being the greatest risk factor for cyclodialysis cleft, Dr. Lee said that it goes without saying that surgeons should take particular care in maintaining a pristine view of the angle. "Don't go where you can't see," Dr. Lee said, noting that measures to increase visibility include turning the patient's head and scope adequately to maintain an en face view of the angle. Dr. Van Tassel also said that good visualiza- tion of the angle is paramount. She said to stop immediately if the wrong anatomy becomes en- gaged or if the patient experiences discomfort. "Angle surgery should be painless," she said. If the trabecular meshwork is pale, Dr. Lee advised staining the target tissue with trypan blue or inducing blood into Schlemm's canal. He said trypan blue is preferable because it is more reliable and avoids the potential for excess bleeding, which could further complicate the view and procedure. 'Pinnacle of MIGS-related complications' dissected continued on page 94

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