October 2017

GLAUCOMA

Broadening the glaucoma surgical plate


by Maxine Lipner EyeWorld Senior Contributing Writer


Dr. Okeke discusses a routine Trabectome procedure illustrating the ability to ablate nearly 180 degrees of trabecular meshwork with the Trabectome handpiece.

Gonioscopic view of CyPass Micro-Stent in good position in the angle

The mechanism of action for the iStent is to act as a conduit bypassing the area of trabecular meshwork, known to be an area of high resistance for outflow.
Source: Constance Okeke, MD

Surgeon shares MIGS success secrets

The acronym “MIGS” seems to be everywhere today in ophthalmology, although only approximately 20% of anterior segment surgeons are currently performing this, according to Constance Okeke, MD, assistant professor of ophthalmology, Eastern Virginia Medical School, Norfolk, Virginia. Among those in the glaucoma world, use is far greater, she thinks. No matter where you are on the microinvasive glaucoma surgery (MIGS) adoption spectrum, here are some success secrets to consider.

At the start

For those who are just beginning to consider MIGS, the first step can be as simple as deciding to perform a certain procedure. “One just has to say, ‘I’m going to enhance my armamentarium starting with one MIGS procedure,’” Dr. Okeke said.
It also comes down to giving patients a “MIGS choice,” Dr. Okeke said. This is akin to the options practitioners now offer with premium IOLs and astigmatism correction. “We’re used to the concept of: ‘If patients are comfortable and controlled on their drops and I have to do cataract surgery, let me just do cataract surgery and keep them stable on their drops,’” Dr. Okeke said, adding that many such patients would opt for MIGS if given the choice.
For many, the next question is which MIGS procedure to attempt first. She started with the Trabectome (NeoMedix, Tustin, California), which she thinks is natural for beginners. In her book, The Building Blocks of Trabectome Surgery Volume 1: Patient Selection, she guides practitioners of all levels through patient considerations and provides case studies and pearls with this and other MIGS devices.
One of the things she likes best about the Trabectome is its ability to provide the surgeon with an excellent view, something that she finds particularly important for novices. She attributes some of this to the Trabectome’s irrigation and aspiration system. “The system provides the fluidics to maintain a stable chamber throughout the procedure. What’s important about that is once the eye is well pressurized, it enables you to have a clear view of the angle,” she said, adding that the fluidics also mean that there’s minimal or no blood in the eye while doing the procedure.
She finds that even beginners can get good long-term results with this because it is kind in terms of wound healing. In her experience, the Trabectome, along with adequate use of steroids early on, tends to cause less scarring through its use of electroablation to seal the leaflets remaining where the trabecular meshwork tissue is removed. “I get much more open clefts when I look at patients years later with the Trabectome compared to my results with some of the newer meshwork removal devices,” Dr. Okeke said.
Many new MIGS practitioners might begin with the iStent (Glaukos, San Clemente, California). One issue with this for beginners could be the insertion technique, which is typically done after cataract surgery. “The corneal incision that’s made for cataract surgery is a lot wider than the width of the handpiece for the iStent,” Dr. Okeke said.
A new surgeon getting used to using a gonio lens in one hand and holding the iStent in the other can inadvertently put a lot of pressure on the wound. This can cause egress of the viscoelastic that’s supposed to keep the chamber maintained. “You’re getting ready to place the iStent and you might touch the trabecular meshwork and it starts to bleed and your chamber is getting more shallow because you’re putting pressure on the wound and viscoelastic is coming out,” Dr. Okeke said. “Suddenly, you have corneal folds and you can’t see and you have to stop, go back in, and put more viscoelastic in.”
To avoid this, Dr. Okeke recommends putting the iStent in first and then proceeding with the cataract surgery. “If you do the iStent first, you use a smaller blade,” she said, adding that this tighter wound protects against egress of fluid and ultimately allows for a better view when trying to place the iStent. While some worry about iStent dislodgement, Dr. Okeke has not found that to be an issue.
Proper patient selection is important for starting out with the iStent. “Patients who have ocular hypertension, early primary open angle glaucoma, who are stable on one or two medications tend to be the ones who I find do best,” Dr. Okeke said, adding that if the iStent is being used for those who have more moderate or even severe glaucoma, practitioners may find they don’t get the results they want. This may cause them to feel disgruntled about how the approach is working with the single iStent that is currently approved for use. A major strength of the iStent is the ability to get a stable patient off at least one medication, which can greatly improve his or her quality of life.

More versed users

Those who are more intermediate MIGS users may take things up a notch. In more aggressive glaucoma cases, if they can’t do an iStent but aren’t ready to do a trabeculectomy or tube shunt, physicians may consider other MIGS. Dr. Okeke finds that procedures such as the Trabectome, the Kahook Dual Blade (New World Medical, Rancho Cucamonga, California), the Trab360 (Sight Sciences, Menlo Park, California), and gonioscopy-assisted transluminal trabeculotomy (GATT) can treat a wider range of patients. “I think that for physicians who have a MIGS procedure down, they have the technical skill set to adopt another procedure that may have another mechanism of action.”
The CyPass (Alcon, Fort Worth, Texas), for example, goes in a different portion of the angle, the suprachoroidal space, she explained. The Xen Gel Stent (Allergan, Dublin, Ireland) can also provide another step before going to a trabeculectomy or tube shunt.
Advanced users can consider combining procedures. For example, since a Baerveldt glaucoma implant (Johnson & Johnson Vision, Santa Ana, California) is closed initially until a suture dissolves or is pulled out, Dr. Okeke sometimes combines this with a Trabectome. That way she obtains a pressure reduction immediately while waiting for the Baerveldt to open.
Those who are more experienced should also keep in mind that sometimes a MIGS device can be used in more than one way. “There have been situations where someone has peripheral anterior synechia in the angle where there is some scar material. The Trabectome handpiece works great in removal of synechia,” Dr. Okeke said. “You can use the instrument for synechia lysis.” Using the tip of the handpiece to remove pieces of iris that are sticking to the angle can open this up, and one can follow by removing the now exposed trabecular meshwork.
For more advanced iStent users, better targeting of episcleral vessels, which can be seen at the time of surgery, can improve outcomes. Dr. Okeke uses a marking pen to indicate where the most prominent of these are and extends the marks to the surface of the cornea. That way, she can see where the marks are and can target those, placing the iStent in that area to maximize efficacy. “I put the iStent near one of the outflow channels, which is represented by those episcleral vessels, so that I can get the most outflow,” she said.
Dr. Okeke encourages practitioners of all levels to get involved with MIGS. “I think there’s a lot of excitement right now and that users should jump in. They need to decide that they’re going to adopt a procedure and contact the company so that they can get started,” she said. “MIGS has changed the way I treat glaucoma in such a positive way for my patients and for myself.”

Editors’ note: Dr. Okeke has financial interests with Alcon, Glaukos, and NeoMedix.

Contact information

Okeke
: iglaucoma@gmail.com

Broadening the glaucoma surgical plate Broadening the glaucoma surgical plate
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