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Cover Focus | May/June '18

On the Front Lines of MIGS

I practice comprehensive ophthalmology in a metropolitan area with 800,000+ residents and only two fellowship-trained glaucoma specialists within 50 miles of the urban center. Many of my patients are in the working class, and they may not be able to afford to take a day (or more) off of work to travel more than 4 hours round trip to see a glaucoma specialist for surgical care. As a result, microinvasive glaucoma surgery (MIGS) has assumed a large role in my practice so that I can try to do as much for my patients before referring them out of town to a glaucoma surgeon.


I started doing MIGS procedures during my third-year glaucoma rotation in residency, as I had several attendings who were comfortable with the »iStent (Glaukos), endoscopic cyclophotocoagulation, and the »Trabectome (NeoMedix). I was able to try all of these technologies in a safe, supported environment, and both the local surgical representatives and my attendings gave me great tips to perform these procedures successfully.


Currently, in practice, my MIGS procedure of choice is the iStent due to its availability and ease of use. Although limited by its need to be combined with cataract surgery, the iStent is a simple and safe procedure that can provide additional IOP lowering for patients with mild to moderate glaucoma who need cataract surgery.

When I learned to perform the procedure, visualization of the angle was emphasized, and I have found that this is a vital component to success. When starting a case, I ensure that the incision is not too long. During the case, I try to prevent hydration of the wound with my phaco handpiece (I place the iStent after insertion of the IOL). When placing the stent, I make sure the patient’s head is adequately turned and the microscope tilted appropriately. I turn the microscope illumination to its maximum and visualize the angle under high magnification. It is important to have a light touch with the gonioscopy prism to prevent corneal striae from obstructing the view.

By following these steps every time, success is almost guaranteed. One aspect of iStent placement that I am still working on is targeted placement of the stent. I typically place a left-handed stent in the superotemporal (right eye) or inferonasal (left eye) angle, but I am learning to recognize anatomic landmarks that may indicate the presence of episcleral veins. Stents placed in the vicinity of these veins may result in improved outflow. The accompanying video demonstrates some of the adjustments I have made over the past few years in maximizing my view. Noticeably, the illumination is brighter, magnification is higher, and focus is tighter (and my hand is steadier!).

Video | iStent placement from case 1 (2015) to case 42 (2018).

A Point of Advice

"We are entering an era where optimizing MIGS procedures is critical. Thinking about iStent placement to potentially maximize postoperative outcomes is something we teach once our trainees are comfortable with placing these devices properly."

Arsham Sheybani, MD

At our surgery center, we also offer goniotomy with the »Kahook Dual Blade (New World Medical). I personally have not done any cases yet, but I am looking out for patients who may be appropriate candidates. My philosophy is to try to preserve the angle structure as much as possible (via medical therapy, selective laser trabeculoplasty, or iStent implantation) prior to angle-destructive procedures such as goniotomy.


Other MIGS procedures that I may consider performing in the future are ab interno canaloplasty and »Xen Gel Stent (Allergan) implantation for more advanced cases of glaucoma. I am also looking forward to the next generation of stents from Glaukos, including the iStent Inject, »iStent Supra, and iDose. These devices will provide additional options for patients, including those with more advanced glaucoma. Because of my experience with MIGS early in my career, I feel confident learning these new procedures and incorporating them into my surgical practice.

Andrew A. Kao, MD
  • Private practice, Empire Eye and Laser Center, Bakersfield, California
  • akao@empireeyeandlaser.com
  • Financial disclosure: None acknowledged