Eyeworld

51 EW FEATURE August 2018 • Glaucoma's armamentarium "In terms of efficacy, the more places you can either stent open or bypass the trabecular meshwork completely will lead to greater effi- cacy," Dr. Wallace said. "However, unroofing of the trabecular mesh- work for a significant number of clock hours does increase the risk of bleeding." For that reason, such proce- dures may not be the best choice for patients who are on anticoagulants. In addition, these procedures are not good choices for patients who will have difficulty with maintaining head-up positioning (which helps postoperative hyphema clear faster) or who need quick visual recovery, Dr. Wallace said. Dr. Radcliffe noted, however, that with trabecular blood reflux, the resulting hyphema is not tech- nically bleeding, which is usually associated with vascular damage and failure of coagulation. Reflux bleeding is caused by an intraocu- lar pressure lower than episcleral venous pressure. This blood reflux is typically seen in the early postoper- ative period after trabecular proce- dures and has not been definitively linked to anticoagulant use. Dr. Wallace prefers the use of viscocanaloplasty if the patient is pseudophakic or a trabecular bypass procedure with a stent for phakic patients undergoing cataract surgery. Dr. Radcliffe said another key consideration is that the goniotomy and canaloplasty procedures do not need to be performed at the same time as cataract surgery. "It makes sense that the practitioner who is also treating glaucoma patients would want to be using both stents and the procedures to best tailor options to a patient, taking into account the cataract status, health insurance, and disease state," Dr. Radcliffe said. Meshwork options The surgical options offer differ- ent approaches to the trabecular meshwork—opening it up (stent or goniotomy), tearing it open (trabec- ulotomy), and dilating it mechan- ically (scaffold or with viscoelastic canaloplasty). Dr. Radcliffe described the stent- ing of the trabecular meshwork as straightforward and the most widely learned approach. "It has advantages in terms of safety because a very small opening is created, and the likelihood of bleeding is almost negligible. The only potential disadvantage is that you are stenting such a small area in the meshwork that it may matter if you get close to a channel," Dr. Radcliffe said. A typical goniotomy creates a large enough opening to hit four or five collector channels. "You can access a lot of area," Dr. Radcliffe said. "Some of the outcomes we've seen with goniotomy have had a favorable safety performance." Tearing the trabecular mesh- work open for several clock hours or 360 degrees through trabeculotomy allows for the greatest access to the canal, Dr. Wallace said. "However, if the canal has become collapsed/stenotic, mechan- ical dilation with either a scaffold or viscoelastic may help improve functionality," Dr. Wallace said. Dr. Radcliffe noted the disad- vantage of the approach is that "unlike a Kahook goniotomy, where a pure strip of trabecular meshwork has been removed, there is a chance that things will scar because those two leaflets can meet each other." Dilating the canal through canaloplasty makes a lot of sense because the canal is not always con- tiguous for 360 degrees and because the collector channels can get small and close off, Dr. Radcliffe said. "It does make sense in some cases to combine goniotomy with canaloplasty to both open up the canal and expand the distal portions of the canal and collector channels," Dr. Radcliffe said However, the lack of compar- ative data with these techniques leaves it up to surgeons "to balance their skills with the technology available to them and to each pa- tient's needs," Dr. Radcliffe said. What to open A fundamental question regarding the canal remains whether to open one area, a few areas, or the whole canal for maximum IOP reduction. "There's conflicting evidence on whether the entire canal needs to be opened," Dr. Radcliffe said. Research on the Trabectome suggests the possibility of significant IOP reduction by only opening one quadrant of the canal. Dr. Wallace noted that research has shown the use of multiple iStent devices produced more IOP reduction than a single device. The improvement is much greater when a second is added compared to the addition of a third stent, Dr. Radcliffe said. The iStent inject will have two stents. In Dr. Wallace's experience, GATT is able to achieve significant IOP lowering—into the low teens with no drops—by opening the entire canal. "However, this does not occur for every glaucoma patient," Dr. Wallace said. "So if Schlemm's canal is atrophic and can't be viscodilated, these minimally invasive procedures will be less successful." EW Editors' note: Dr. Radcliffe has finan- cial interests with Glaukos, Alcon, Allergan, Ellex, Sight Sciences, New World Medical, and Iridex. Dr. Wallace has no related financial interests. Contact information Radcliffe: drradcliffe@gmail.com Wallace: danajwallace@gmail.com Poll size: 97 As an ophthalmologist, if I had cataract and severe glaucoma with borderline IOP control, I would ask my surgeon for: A cataract extraction with trabeculectomy A cataract surgery with a subconjunctival gel stent A cataract surgery with a supraciliary stent A cataract surgery with a trabecular meshwork stent Regarding trabecular meshwork MIGS procedures: I don't perform trabecular meshwork procedures I perform one procedure only I perform a few different procedures I perform many different procedures from stents to goniotomy and canaloplasty

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