Choosing a Winner for You and Your Surgical Patient

Considerations for learning and incorporating MIGS.

The world is changing. Social media has altered how patients see and interact with their health care providers. Expectations are high, and instant results are considered almost a given. As we wade into the waters of surgical choices for our glaucoma patients, there are many outside factors to consider. For example, many patients undergoing cataract surgery would be reluctant to pick a vision-reducing option. Even the delay in visual recovery seen with a trabeculectomy may be unacceptable.

This article explores the choices glaucoma specialists make regarding less invasive or microinvasive glaucoma surgery (MIGS) procedures. Often these choices are “labeled,” such as those used at the time of cataract surgery. New surgeons pay close attention to how to approach the patient, more experienced glaucoma surgeons see a broader picture of options, and glaucoma specialists in different geographic locations have different methods. All are a part of what our patients are hearing about as the Internet creates a global marketplace for discussions about MIGS.


Aakriti Garg, MD

Expanding therapeutic options are a breath of fresh air in glaucoma care, and fellowship is the ideal time to be exposed to these. As a clinical fellow at The Wilmer Eye Institute, I select therapeutic options for patients as part of our assessment. Having the option to offer MIGS leads young surgeons through a thought process in weighing the risks and benefits of these newer glaucoma surgeries. As I enter into my final year of training, I have begun to reflect on the role MIGS will play in my practice. The questions that come to mind include the following:

  1. How do I learn MIGS in a way that doesn’t compromise patient safety? I am fortunate to work with faculty members who are talented in the operating room and are enthusiastic about passing on skills to trainees. If I were not part of a large academic institution, working with proficient users of MIGS may not have been possible. While device and procedure representatives can train surgeons with computer modules and wet labs, I would think twice before offering surgeries that I have not yet mastered.
  2. How do I explain surgical complications to patients after MIGS procedures? Patients may have different expectations after MIGS procedures. The description “minimally invasive” invokes an assumption that these surgeries have minimal postoperative recovery periods and complications. However, we know that recurring hyphema, conjunctival erosion, endothelial cell loss, and more are outcomes of these procedures. We must explain to patients preoperatively that MIGS is not a simple “add on” to cataract surgery, and procedures can have serious adverse effects.
  3. What will be the long-term outcomes of MIGS procedures? There are few clinical trials on MIGS, and fewer still provide long-term safety and efficacy data. The recent release of CyPass (Alcon) 5-year outcomes data and subsequent voluntary withdrawal of the device adds further doubt to the long-term efficacy and safety of new procedures. Explaining that we do not know all (or any) answers in regard to long term ramifications seems like an important topic of discussion.
  4. What if additional measures are needed? I frequently see patients who experience some benefit after their MIGS procedure but require additional medical or surgical treatment. We then have to explain to the patient the importance of additional medical or surgical treatment along with its additional risks and costs. Doing a more definitive procedure as the first step may have prevented this additional round of surgery.
  5. What if the implantation of a MIGS device prevents a more definitive procedure from being performed? Real estate in the eye is valuable, and if it is used by procedures that don’t provide long-term pressure reduction, we may be out of options. For example, if a patient with conjunctiva scarred due to a Xen implant (Allergan) cannot undergo a subsequent trabeculectomy or tube implant, our next steps in treatment will be limited. Despite these concerns, I am fortunate to be able to offer options that allow for the personalization of care to the individual patient’s ophthalmic needs. Gaining proficiency in the preoperative discussion of risks and benefits, surgical procedures, and postoperative care and management of complications of a wide variety of glaucoma surgeries early in our careers gives us the opportunity to master important treatment options for the future.


Jithin Yohannan, MD, MPH

I was fortunate enough to complete my glaucoma and anterior segment fellowship at University of Toronto/Prism Eye Institute. Although Canadian hospital budgets are capitated, due to the hard work of Dr. Ike Ahmed and others on his team we had access to a variety of MIGS devices at our surgical sites. Devices and procedures I had experience with as a fellow included the following: iStent and iStent inject (Glaukos), Hydrus (Ivantis), Kahook Dual Blade (New World Medical), gonioscopy-assisted transluminal trabeculotomy (GATT), CyPass, Xen (Allergan), and InnFocus (Santen), as well as traditional trabeculectomy and tube-shunt surgery. Some of these devices are FDA approved and some are still undergoing trials.

I’ve recently started a position as a faculty member at Wilmer Eye Institute, and practicing back in the United States, particularly in a hospital-based setting, presents a variety of challenges with regard to access and reimbursement for MIGS devices. However, with appropriate planning and patient selection, many of these challenges can be eliminated. Below I discuss 2 challenges and how each can be overcome with appropriate planning.

Access to Devices

For surgical IOP reduction via improved outflow dynamics, there are 3 different pathways a surgeon can target: (1) trabecular bypass, (2) suprachoroidal space, and (3) subconjunctival space. The choice of each pathway should be guided by the patient’s target IOP and whether glaucoma progression is occurring. It is possible to find an available device or procedure in the same pathway when a specific device is not available. As the only available suprachoroidal device in the United States and Canada (CyPass) has been withdrawn from the market, I will focus my discussion on trabecular bypass/subconjunctival devices.

Trabecular bypass devices and procedures (iStent, iStent inject, Hydrus, Kahook Dual Blade, GATT) cannot achieve IOPs lower than episcleral venous pressure (EVP) which is typically around 8 mmHg to 10 mmHg. I prefer to limit implantation of trabecular bypass devices and other trabecular bypass procedures to either patients who have a target IOP in the mid teens without rapid glaucoma progression or patients with well controlled glaucoma who desire medication reduction. Although there are minimal comparative trials assessing these trabecular bypass procedure/devices, I believe they achieve clinically similar IOP lowering. Therefore, if one device is not available, an alternate trabecular bypass device or procedure can be substituted.

Subconjunctival MIGS devices (Xen, InnFocus) are not limited by EVP and use the same bypass pathway that is utilized by conventional glaucoma surgeries (trabeculectomy and tube shunt). The IOP these devices can achieve is limited by the implant diameter and length (Poiseuille’s law) and conjunctival wound healing and fibrosis. In the absence of conjunctival wound healing, both devices can achieve IOPs in the single digits. With correct patient selection, careful surgical technique, and perioperative management, we are able to achieve IOPs of low teens in many patients undergoing Xen or InnFocus with MMC. The InnFocus device is not available in the United States, but has been our go-to device in Canada for advanced or progressive disease. However, we readily offer Xen surgery to patients with IOP targets in the low teens or patients with advanced or progressive disease. In the correct patient population (older, thin tenons) ab-interno Xen offers excellent results and it is available in the United States. For younger patients with thicker tenon’s where fibrosis might be a larger issue, one might consider doing external dissection of the conjunctiva and tenons, placing mitomycin sponges under tenons, and placing the Xen in the subtenon space with separate closure of conjunctiva and tenons to prevent impingement of the implant. Another alternative is performing a traditional filtering procedure.

Reimbursement When Working in a Hospital Setting

In Maryland, hospital budgets are capitated, and many insurers as well as the hospital will have issues related to the cost of devices such as the iStent, Xen, or Kahook Dual Blade. Ambulatory surgery centers (ASCs), with their lower operating expenses and lower overall charges to insurers, are, in most cases, able to bill and get reimbursed for the FDA-approved MIGS devices. Therefore, I try to schedule all MIGS in the ASCs associated with our eye institute rather than in the hospital-based surgery center. Even using the ASC, there may be issues related to the non-Medicare patient having approval at all for any location. Prior authorization is a must.

If operating at an ASC is not an option and insurers will not reimburse for MIGS devices, learning to perform alternate cost-effective procedures is critical. For trabecular bypass, goniotomy can be performed with a 25-gauge needle with a bent tip (this mimics the dual blade action of the KDB). Alternately, a 5-0 Prolene suture can be used to perform GATT or 180-degree GATT (aka hemi-GATT). For these procedures, the initial capital outlay would involve buying a gonioprism as well as micro instruments for the anterior segment, but subsequent incremental cost per case would depend on the ophthalmic viscosurgical device, needle, and suture and thus may be comparable or even more cost effective than traditional trabeculectomy and tube-shunt surgery. If a subconjunctival device (ie, Xen) is not available for a procedure on a patient with advanced or progressive disease with a low target IOP, then trabeculectomy and tube-shunt surgery remain excellent options.


Antonio Maria Fea, MD, PhD

The adoption of MIGS throughout Europe is very patchy and depends on rules and regulations of different countries. Early work on MIGS was done in Spain, Italy, and Germany. Despite investigations and CE Mark approval, the widespread adoption of these procedures has been delayed in Italy due to the absence of a specific reimbursement code. Another obstacle to the widespread use of MIGS in Europe has been the general lack of acceptance by leading glaucoma specialists who continue to compare all minimally invasive surgery to traditional methods. Additionally, there is poor commercial penetration into the European market by small start-up companies. That landscape has partially changed since the acquisition of the Aquesys XEN45 by Allergan. We now hear more about MIGS. Subconjunctival outflow has been more accepted because it is more similar to traditional surgery, with the added promise of a lower postoperative IOP. The long-term relationship, the dedication of Allergan to the glaucoma field, and the company’s widespread commercial penetration also played an essential role in the adoption of the Xen throughout Europe. Trabecular bypass or excision surgery remains limited mostly to the United Kingdom, Germany, and Spain.

Changing the Paradigm

The publication of longer-term results will certainly help to encourage skeptical surgeons to try MIGS. However, economic and bureaucratic issues might still hinder adoption. For example, some countries do not have a specific reimbursement code, and using a general code does not cover the expense of the surgery due to the relatively high device cost. Countries that do not have a diffuse insurance system may fall behind in the adoption of new devices, especially if the health system does not allow the patient to co-pay for the devices. However, the potential for MIGS across Europe is great: few newer drugs have been released in the last few years and the ones that will be introduced in the near future may actually have an additional potential effect (maybe good, maybe bad) on some of the Schlemm’s canal devices. Compliance and adherence to therapy is a huge issue in Europe, and the observation that long-term effects of traditional surgery may be limited over time certainly opens the door to introducing earlier surgery. Newer methods to investigate the outflow or to predictively diagnose early signs of bleb failure are also warranted to improve our surgical treatment.

Patient Selection

I have limited experience with suprachoroidal surgery, and I have had good experience with trabecular and subconjunctival devices. I prefer implanting devices in Schlemm’s canal rather than avulsion or eradication of the trabecular meshwork. Within these limits (ie, trabecular stents and subconjunctival surgery) I usually consider Schlemm’s canal surgery when I believe that the target pressure can be around 15 mmHg, and I use a subconjunctival device if I aim for a lower target. If the patient’s target needs to be in the low teens, I still proceed with trabeculectomy in most cases.

The panorama of patients whom I consider for Schlemm’s surgery is wide, including those who have problems with topical therapy, those suspected of being poorly compliant, or those looking for an alternative to their current therapy. If patients are on maximal medical therapy (3 or more eye drops), with a pressure in the high teens, I usually do not promise complete cessation of medical therapy. I generally do not use a MIGS procedure in patients who already failed a trabeculectomy, except for very select cases (conjunctiva still very mobile in the nasal quadrant, patients who are not willing to proceed with any “maximally” invasive surgery because of previous complications, or very old or seriously ill patients in whom the surgery is mainly aimed to delay visual loss).


E. Randy Craven, MD, FACS

My coauthors here have pointed out very good considerations and practicalities. Dr. Garg describes the time needed to learn and concerns about starting these new procedures. If adverse events happen, it seems like traditional filtering surgery may have not looked so bad. However, when the number of MIGS options are done at a higher volume, as pointed out by Dr. Yohannan, MIGS starts to make sense based on treatment goals. Financial issues are extremely important for all of us in the MIGS world. Dr. Fea points out that this is not limited to the United States, and the influence of a well trusted partner in ophthalmology brings in more confidence and interest in MIGS.

Another area worth exploring is removal of the trabecular meshwork (extirpation). We have data from the trabectome.1 Some have questioned the validity of a registry controlled by the company. Gonioscopic-assisted transluminal trabeculotomy seems to show efficacy in juvenile, congenital, uveitic, steroid-induced glaucoma and potentially those with failed tubes. Other blade cutting devices, such as a twin blade, may have some use for pseudophakic and exfoliative patients. Regardless, there is some evidence that removing the meshwork may have usefulness in cases where bypassing may not lead to success. Dilating the canal (canaloplasty) has the potential benefit of preventing hyphema if a trabeculotomy (or goniotomy) is done. Additionally, some patients may have limited collector system outflow. Perhaps dilating that may help.

Imaging of the anterior segment, dyes, and other methods of locating outflow failure will undoubtedly help us pick a targeted MIGS. Others may choose to bypass the whole outflow system (Xen or InnFocus) or choose the suprachoroidal pathway. GP


  1. Minckler DS, Baerveldt G, Alfaro MR, Francis BA. Clinical results with the Trabectome for treatment of open-angle glaucoma. Ophthalmology. 2005;112(6):962-967.