In this installment of Interventional Mindset, Paul Singh, MD, from The Eye Centers of Racine and Kenosha, talks about his experiences using the Omni device, a tool used in minimally invasive glaucoma surgery (MIGS). It viscodilates to open the Schlemm’s canal and distal collector channels simultaneously, allowing the surgeon to perform a cutting procedure.
This article will review patient selection issues, intra-operative pearls, and post-operative management to help with successfully implementing the Omni device.
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Pre-operative tips for MIGS patient selection
When considering a patient for an Omni procedure, at the time of the preoperative assessment, it can be difficult to know where the resistance to outflow originates. Ultimately, a combination of disease and resistance staging will help eyecare providers select the appropriate procedure for the patient’s unique needs.
A study from Haiyan Gong showed that 50% of patients with primary open-angle glaucoma have complete herniations or blockages of the ostial opening into the collector channels. So when considering a patient, if you simply put a stent in the Schlemm’s canal, or perform a pre-operative selective laser trabeculoplasty (SLT), you may not have the impact you want if the canal is collapsed or if the distal channels are fully blocked from the Schlemm’s canal.
Breakdown of conventional outflow MIGS
Clinicians who perform MIGS procedures are lucky to have many options to tailor the necessary procedure to the patient. The Omni device allows surgeons to open the Schlemm’s canal, viscodilate, break the herniations in the Schlemm’s canal, and then push viscoelastic to flush out the entire outflow system.
Outflow stents: Approved at the time of cataract surgery.
- iStent Inject
- Hydrus
Dilation of the outflow system: Approved with cataract surgery and as a stand-alone treatment.
- iTrack/ABiC
- Visco 360/Omni
Trabecular meshwork stripping/removal: Approved with cataract surgery and as a stand-alone treatment.
- Kahook Dual Blade/Trabectome
- GATT/Omni
Surgical video of viscodilation with the Omni
In this first example, a 360-degree viscodilation and 180-degree otomy were performed, this combination of procedures was chosen based on the patient’s background. The 180-degree otomy was selected to limit the risk of intra- or post-operative hyphema. The patient was pseudophakic, on four classes of medication, and their intraocular pressure (IOP) was in the lower 20s. Also, the patient underwent an SLT and had a moderate response.
The goal was to get the patient’s IOP to the lower teens, and because the patient was not compliant with medications, this procedure also offered the potential to take the patient off some of their medications. Based on the patient’s past SLT, Dr. Singh concluded that the resistance was beyond the trabecular meshwork (TM) in the Schlemm’s canal and distal channels.
An important part of the procedure is to get a good en face view with the trabecular meshwork facing towards the surgeon, almost perpendicular, instead of downward. It’s also helpful to engage the TM at about a 45-degree angle and aim the loader toward the nasal angle.
Figure 1 is a still from a surgical video of Dr. Singh using the Omni device to viscodilate a pseudophakic patient’s eye.
Figure 1: Courtesy of I. Paul Singh, MD.
How to prevent intra- and post-operative hyphemas
It’s important to remember that with any cutting procedure, hyphemas can occur. To manage this, Dr. Singh recommends hyperinflating the eye with viscoelastic, waiting a minute or 2, and then slowly switching between decompressing and waiting to equilibrate the eye.
How to bill for combined MIGS procedures
The Omni device combines two mechanisms of action (viscodilation and cutting), but these procedures are now billed together. However, pairing stenting with viscodilation can be combined in billing because the stent is a T code, and the Omni/viscodilation is a level 1 code. Pairing these two procedures works synergistically by flushing out the entire outflow system and maintaining patency with stenting.
Surgical video of viscodilation and the iStent
In this surgical video, Dr. Singh used the Omni loader to perform a 360-degree viscodilation to flush out the patient’s outflow system and then place an eye stent. After using the Omni, the iStent inject is inserted, which must be used carefully because pushing the stent too hard can over-implant it and stretch open the canal.
After the stenting was complete, blanching was noted around the eye, demonstrating the patient’s improved outflow facility. Using viscodilation and the iStent, the chance of hyphema decreases when compared to a cutting procedure.
Surgical video of viscodilation and the Hydrus
This surgical video is of a cataract patient in their 30s, on multiple medications, with mild to moderate glaucoma. Dr. Singh wanted to give the patient a chance to get off medications, so he recommended a combination of MIGS procedures.
He performed a 360-degree viscodilation with the Omni device using a clear en-face view, pointing the catheter at a 45-degree angle towards the TM to engage the Schlemm’s canal. Afterward, he used the Hydrus to perform a 180-degree otomy through the uncut trabecular meshwork to maintain the patency of the viscodilated area and to scaffold the Schlemm’s canal.
This was an example of combining multiple mechanisms of action to benefit a patient that required full outflow facility enhancement, as post-operatively, the patient’s IOP dropped to 14mmHg while off medications (compared to 30+mmHg on them).
Although MIGS procedures will not always work out that way, this example reflects the reality that many conventional outflow procedures result in patients with IOPs in the middle teens. It’s been observed that performing cataract surgery with a stent and viscodilation helps improve the chances that patients will be off medications long-term.
Surgical algorithm for stents, viscodilation, and goniotomy
When deciding which MIGS procedure is the best fit for a patient, Dr. Singh highlighted that the general rule he follows is: the more advanced the disease progression or, the higher number of medications a patient has, the more likely he’ll perform an otomy.
Conversely, for more mild cases, such as phakic patients with no cataracts, he prefers to perform viscodilation to limit the otomy. It’s important to note that these are not steadfast rules, they simply represent an outline of how to approach MIGS procedures that is further broken down below.
Figure 2 is a procedure algorithm to use when deciding which MIGS procedure is the best fit for a patient.
Figure 2: Courtesy of I. Paul Singh, MD.
Pearls for MIGS post-operative management
When managing patients during the post-operative period, it’s important to be able to identify and understand the differences between hyphema and inflammation. Often, if a hyphema is present, it’s best not to bump up the steroids in response, as hyphemas are made up of red blood cells (instead of inflammatory cells).
Also, it’s important to inform the patient ahead of time of the potential side effects of performing a procedure that makes a connection to the bloodstream because there’s always a chance that blood will reflux in the eye as a result of the postoperative decreased eye pressure.
Dr. Singh noted that he usually tries to take patients off their glaucoma drops if they have mild to moderate glaucoma and follows up with them after a day, week, and month. For more advanced patients, Dr. Singh keeps them on aqueous suppressants to stop the prostaglandin analog (PGA) and then treats them as needed.
