EyeWorld Asia-Pacific December 2018 Issue

lants. In addition, these proce- dures are not good choices for patients who will have difficulty with maintaining head-up posi- tioning (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 technically bleeding, which is usually associated with vascular damage and failure of coagula- tion. Reflux bleeding is caused by an intraocular pressure lower than episcleral venous pressure. This blood reflux is typically seen in the early postoperative period after trabecular procedures 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 cata- ract surgery. Dr. Radcliffe said another key consideration is that the gonioto- my 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 pa- tients 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 (trabeculotomy), and dilating it mechanically (scaffold or with viscoelastic canaloplasty). Dr. Radcliffe described the stenting of the trabecular mesh- work as straightforward and the most widely learned approach. “It has advantages in terms of safety because a very small open- ing 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 chan- nel,” 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. Rad- cliffe said. “Some of the outcomes we’ve seen with goniotomy have had a favorable safety perfor- mance.” Tearing the trabecular mesh- work open for several clock hours or 360 degrees through trabeculot- omy allows for the greatest access to the canal, Dr. Wallace said. “However, if the canal has be- come collapsed/stenotic, mechani- cal 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 contiguous for 360 degrees and because the collector channels can get small and close off, Dr. Rad- cliffe said. “It does make sense in some cases to combine goniotomy with canaloplasty to both open up the canal and expand the distal por- tions of the canal and collector channels,” Dr. Radcliffe said. However, the lack of compara- tive 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 added. 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 signifi- cant IOP reduction by only open- ing one quadrant of the canal. Dr. Wallace noted that re- search has shown the use of mul- tiple 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.” EWAP Editors’ note: Dr. Radcliffe has financial interests with Glaukos, Al- con, 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 Trabecular out ow – from page 33 34 EWAP SECONDARY FEATURE December 2018