Eyeworld

43 EW FEATURE May 2016 • Microinvasive glaucoma surgery (MIGS) Contact information Bacharach: jbacharach@northbayeye.com Harasymowycz: pavloh@igmtl.com Nguyen: Nguyen.Quang@scrippshealth.org patients successfully, including patients with pseudoexfoliation and pigmentary glaucoma. "Patients are extremely excit- ed about the opportunity to have the ability to reduce the number of medicines after cataract surgery," Dr. Bacharach said. They often enjoy the fact that it's done through the cataract wound and no extra inci- sions need to be made, he added. Patients are also relieved with the iStent's safety profile. Dr. Nguyen said that his success using the iStent can largely be linked to good patient selection, such as those with ocular hypertension, early glaucoma, or patients on 1–3 medications. Patients to avoid are those with more advanced glau- coma, neovascular glaucoma, and similar situations. He added that patient reactions to the iStent have generally been good, with some even coming to him asking for the new technology. In general, Dr. Nguyen said that he will suggest the iStent for those who are the best candidates and has gotten very little hesitation from patients about the device. When to place the iStent Depending on the situation, sur- geons may choose to implant the iStent before or after cataract sur- gery. Dr. Harasymowycz likes to do the implantation before cataract surgery because the cornea is still pristinely clear at this time. He add- ed that this strategy eliminates the need for additional viscoelastic. Dr. Bacharach said he always places the iStent in narrow angle glaucoma after he removes the cata- ract because it ensures that the view of the angle is better during surgery. "In patients with open angle glaucoma, I change my technique to placing the iStent before I do the cataract," he said. Again, this is because the cornea is pristine before the cataract surgery, so there is no corneal edema from the ultrasound. In many cases he can do it without opening a second tube of viscoelas- tic as well. Also, if there is some blood in the eye from iStent place- ment, the surgeon doesn't have to worry about doing a capsulotomy with a small amount of blood in the eye, Dr. Bacharach added. According to Dr. Nguyen, you need to have a "perfect, uncom- plicated cataract surgery" before deciding to place the iStent. If this is not the case and there are complica- tions, he will not implant the device because this could cause further complications down the line. Adjusting patient medications for implantation It's important to consider, both preoperatively and postoperatively, which medications iStent patients are on. In the U.S. clinical trials, sur- geons were free to do whatever they thought best, Dr. Bacharach said, and there was no specific protocol on which medicine to reduce first. "In general, if I have a patient on a prostaglandin and an aqueous suppressant or a fixed combination, I will try to stop the prostaglandin first because I still want the patient to have some reduced aqueous in- flow into the eye," he said. This has been a successful strategy for him. Dr. Bacharach added that if a patient is just on a prostaglandin and everything goes well intraop- eratively, he will stop the drop at the first postop visit, as long as the pressure allows that. Dr. Nguyen proceeds slowly when adjusting a patient's medica- tions. He uses steroids both preoper- atively and postoperatively. He will also use an alpha antagonist after surgery. He recommended keeping patients on their current glaucoma medications and taking them off very slowly. Dr. Harasymowycz advised care- ful consideration postoperatively be- cause he said that around 10–15% of patients develop a steroid response after a week. The surgeon may see patients with extremely high IOP at this time, so he tends to taper the patient off steroids quite early; after 2 weeks, he does not use a steroid anymore. Using a less potent medi- cation, like loteprednol, may be less likely to cause a rise in pressure, he said. Dr. Harasymowycz said that he uses nonsteroidals for a month after the surgery. EW Editors' note: Dr. Bacharach has finan- cial interests with Glaukos. Dr. Nguyen has no financial interests related to his comments. Dr. Harasymowycz has financial interests with Ivantis (Irvine, California). Targeted placement and using multiple stents W hen inserting the iStent, surgeons may want to consider targeted placement for optimal results. Some surgeons even use multiple iStents. The ancillary device used to place the iStent has improved since the initial trials, Dr. Bacharach said. The inserter that the stent is placed with has stiffened a bit and facilitates implantation. The important thing for a new surgeon is to get it in Schlemm's canal. Be comfortable with your arm movements and body position and take your time, he added. As the surgeon becomes more proficient, he or she can look for areas of pigmentation, which is where areas of collector channels seem to be located. The surgeon may also want to look for areas in the conjunctiva where aqueous veins are present and try to do targeted placement in those areas. One way to facilitate placement in Schlemm's canal is by using trypan blue dye staining, Dr. Bacharach said. "This will light up the pigmented trabecular meshwork, and Schlemm's canal sits right behind it," he said. "It will help make sure the surgeon places the stent in the right position." "Visualization is everything to this procedure and any angle surgery," Dr. Nguyen said. The surgeon needs to be good at intraoperative gonioscopy, needs to know anatomy, and needs to identify landmarks clearly, he said. With his work in Canada, Dr. Harasymowycz said he often places 2 iStents. In the U.S., 1 stent is approved, but patients can pay for the second stent. "We have found that an additional stent can lower pressure further and lower the number of medications further as well," he added. The G2 iStent inject was approved recently in Canada. The difference is that the stents are now smaller, Dr. Harasymowycz said. Instead of 1 mm, they are 0.4 mm. Both types come preloaded, but the G2 has a different type of injection mechanism. "Just putting an iStent anywhere in the canal may not be the best," he said. "The surgeon should target areas close to a collector channel." Dr. Harasymowycz suggested looking in the trabecular meshwork for an area with more pigmentation. Sometimes the surgeon can see that just adjacent to the meshwork.

• Cover