Eyeworld

EW GLAUCOMA 42 December 2016 by Michelle Dalton EyeWorld Contributing Writer Everyone agreed using an OVD on the interface is beneficial, and the choice of OVD is not as important. Dr. Moster recommends put- ting "lots of OVD where the limbus meets the cornea" to optimize visu- alization; "this allows for an excel- lent view. Therefore, it is not only the amount of viscoelastic in the anterior chamber that's important, but the amount of viscoelastic under the gonio lens." Surgeons "don't have to work hard to maintain that light feeling" when they use an OVD as a coupling agent, Dr. Grover added. It's common for newer surgeons to put "a little too much pressure on the cornea with the goniolens," Dr. Fellman said. "That causes striae in the cornea, which immediately decreases the view, which makes the surgeon tense up more and put more pressure on the lens." Dr. Sheybani has begun using some of the disposable gonioprisms from Katena (Denville, New Jersey) as the optics are comparable to the reusable prisms, he said. A crucial aspect to keeping good visualization during the surgery is to be able to identify the anatomy pre- operatively in the office, Dr. Fellman said. "If you're new to MIGS and you can't find the spur in the angle that you want to perform surgery, that's probably not a good first can- didate," he said. Incising the trabecular mesh- work will result in blood reflux, which can also obscure the view, so Dr. Grover recommends putting patients in reverse Trendelenburg to help minimize the pressure and reflux into the eye. To block or not to block? Blocks can be beneficial, and Dr. Vold uses topical anesthesia with intracameral lidocaine in all patients undergoing MIGS procedures. Dr. Fellman uses peribulbar blocks "a vast majority of the time" and rec- ommends them to less experienced MIGS surgeons "because handling excessive eye movements when you're working in the angle can be very detrimental to the outcome of the surgery." Although goniolenses are designed to minimize patient movement, "they're not 100% so I prefer peribulbars to topicals," he said. the optics in disposable lenses are as good as those in the reusable ones. His colleague, Ronald Fellman, MD, added the lens is both right- and left-labeled, meaning surgeons don't have to alter their position to use the lens. Being right handed, Marlene Moster, MD, attending surgeon, Wills Eye Hospital, Philadelphia, uses her Swan-Jacob lens in her left hand. "A pearl to good visualiza- tion is to make sure that the head is tilted away from you 30 degrees, but not too much, and the microscope is tilted toward the doctor, but not too much. Any extreme will decrease visualization," she said. Arsham Sheybani, MD, assistant professor, Washington University School of Medicine, St. Louis, Missouri, prefers to use lenses without teeth because "patients can feel them at times." For surgeons who prefer reus- able lenses, Dr. Bacharach said resi- due left by the sterilizer on the lens can be easily removed with an in- strument wipe. "Otherwise, that res- idue is going to obscure the view," Dr. Bacharach said. "Make sure the lens is clean and well-centered, and try not to push too hard as that can create striae in the cornea." optics and are a gentle lens for expe- rienced surgeons," Dr. Vold said. Still other lenses were designed to make goniosynechialysis easier or to improve ergonomics to reduce pressure on the cornea and prevent corneal striae, but they may cause some discomfort or decrease the amount of control a surgeon has if the patient moves, Dr. Vold added. Finally, several single-use lenses are also now available. "Everyone will have a comfort level with four or five options," said Jason Bacharach, MD, North Bay Eye Associates, Petaluma, California. Dr. Bacharach uses the Vold Gonio Lens (Volk Optical, Mentor, Ohio) or the Glaukos open access lens (San Clemente, California)—the former because it won't compress the cornea and the latter because it allows for easier insertion of the handheld delivery device during MIGS. Advantages to the Swan-Jacob goniolens (Ocular Instruments, Bel- levue, Washington), which has been available for decades, include that it's reusable, "and the views can be really good. That's our standard go- to goniolens for most of the MIGS procedures we do," said Davinder Grover, MD, Glaucoma Associates of Texas, Dallas, who doesn't think S urgical management of glaucoma has been forever changed with the intro- duction of microinvasive glaucoma surgery (MIGS), allowing surgeons to better manage and control less advanced stages of glaucoma. These procedures can be performed in conjunction with cataract surgery or as a standalone procedure (depending on the MIGS surgery), and require a keen under- standing of the iridocorneal angle. Gonioscopy—intraoperatively and preoperatively—can help surgeons find the correct anatomical land- marks. Anterior segment imaging is not a substitute for gonioscopy, said Steven Vold, MD, Rogers, Arkansas, referring to a recent Technology As- sessment report from the American Academy of Ophthalmology. Goniolenses Numerous lenses are commercially available. Some have been available for decades, and others have been introduced in the past 10 to 12 years that modify earlier lenses by add- ing a right- or left-hand version or increasing the field of view. Those modified lenses "allow for easier placement in eyes with small pal- pebral fissures; they have excellent Gonioscopy's role in MIGS Gonioscopy views with single-use lenses: (A) four-mirror in clinic; (B) and (C) surgical gonioprism intraoperatively; (D) single mirror intraoperatively; yellow arrow points to area of visible peripheral anterior synechiae Source: Arsham Sheybani, MD Device focus

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