Which MIGS for which patient?

January 17, 2019
Conni Bergmann Koury

Here is one question to help clinicians decide: ‘What is the anatomy giving me?’

Glaucoma surgeons should have at least two or more procedures with different mechanisms of action in their tool kit- techniques that have options for phakic and pseudophakic patients, said Brian A. Francis, MD, MS.

Reviewed by Brian A. Francis, MD, MS

To choose the right microinvasive glaucoma surgery (MIGS) procedure, glaucoma specialists must consider several questions, according to Brian A. Francis, MD, MS.

Among these questions:

  • Is there a coexistent cataract?

  • What is the diagnosis?

  • What is the anatomy?

  • What is the target IOP?

  • What medications can the patient use?

  • What is the patient’s preference and lifestyle?

Glaucoma surgeries can be categorized based on one of four mechanisms of action, according to Dr. Francis, professor of ophthalmology and holder of the Stieger Endowed Chair at the Doheny Eye Institute and Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles (UCLA).

These categories include the trabecular outflow, suprachoroidal outflow, aqueous humor production, and subconjunctival outflow.

Trabecular outflow

Regarding procedures that target trabecular outflow, surgeons can choose Schlemm’s canal dilation, trabecular stents, or trabecular removal with trabeculotomy/ goniotomy. Methods of Schlemm’s canal dilation-which can be done with or without cataract extraction (CE)-include ab interno canaloplasty, a 360° treatment, and viscodilation of Schlemm’s canal with a catheter. This can be accomplished with Visco360 and the Omni procedures (Sight Sciences).

The iStents (generation 1 and 2; Glaukos) and the Hydrus Microstent (Ivantis) are implants that target trabecular outflow. This mechanism can also be approached via Schlemm’s canal unroofing procedures. The technique can be performed with or without cataract extraction, and it can treat a greater amount of the angle.

For 180° of trabecular removal, surgeons can consider the Trabectome or Goniotome (NeoMedix) or the Kahook Dual Blade (New World Medical). Gonioscopy-assisted transluminal trabeculotomy can be used to treat 360°, as can the Trab360 (Sight Sciences) and Omni procedures.

Suprachoroidal outflow

Procedures that target suprachoroidal outflow are combined with CE. They make use of the suprachoroidal space and uveoscleral outflow. The withdrawn Cypass (Alcon Laboratories) is one such device. Currently, the iStent Supra (Glaukos) is under FDA investigation.

Aqueous humor production

Endoscopic cyclophotocoagulation (ECP) targets aqueous humor production, and the technique is targeted and titratable, Dr. Francis noted. It can be done with or without cataract surgery and is performed via anterior or pars plana approaches. It is useful in mild glaucoma as well as ultra-refractory conditions (ECP-plus or combined with other treatments).

The endoscope is useful in other surgical applications to view intraocular anatomy and pathology, he added. Transscleral cytophotocoagulation or micropulse (subthreshold) laser (Iridex) can also be used, according to Dr. Francis.

Subconjunctival outflow

“I consider subconjunctival outflow procedures as less invasive, not microinvasive, because they do produce a bleb and we use mitomycin,” Dr. Francis said.

These are designed to lower IOP similar to traditional filtration such  as trabeculectomy or aqueous tube shunt, but with lower complication rates. These include the ab interno approach (XEN Gel Stent, Allergan) and the ab externo approach with the investigational glaucoma drainage system (InnFocus Micro Shunt, Santen; not yet FDA approved).

Back to the key questions

Is there a cataract?

The MIGS procedures that are FDA approved in conjunction with cataract extraction are the iStent, iStent inject, and the Hydrus.

“In patients on multiple medications, we should consider MIGS along with cataract extraction even if the patient is well controlled to reduce the medication burden,” according to Dr. Francis.

Trabecular MIGS without a device is an option independent of cataract status. Angle-closure glaucoma may improve with cataract extraction alone, he noted. Because ECP is difficult in a phakic eye, it must be performed with cataract surgery or in pseudophakes, Dr. Francis noted.

Diagnosis and anatomy

In primary and secondary open-angle glaucomas, all procedures are on the table, Dr. Francis said.

“In exfoliation glaucoma trabecular outflow is the main problem, so do a procedure that targets meshwork like a stent or removal.”

The same is true of pigmentary glaucoma. In a narrow angle, glaucoma intervention should be combined with cataract extraction if possible, and caution should be exercised with implants.

“In chronic-angle closure, you can consider MIGS plus goniosynechialysis or aqueous inflow or subconjunctival procedures,” Dr. Francis noted.

Target IOP

In Dr. Francis’ experience, angle procedures result in IOPs in the 14 to 17 mm Hg range, suprachoroidal, a 13 to 15 mm Hg range, aqueous inflow procedures can achieve a 30% reduction, and subconjunctival filtration results in pressures 10 to 14 mm Hg.

“Do not forget that procedures can be combined for greater efficacy in patients with more advanced disease in need for lower target IOPs,” he said. “Patients intolerant to medications also require more aggressive treatments.”

Conclusion

Dr. Francis said he believes that glaucoma surgeons should have at least two or more procedures with different mechanisms of action in their tool kit-techniques that have options for phakic and pseudophakic patients.

“Trabecular outflow procedures are usually first line,” Dr. Francis said. “Aqueous inflow procedures are versatile.”

He said that surgeons should think about combining procedures and always know what they want to accomplish for each patient, based on what the eye is “giving you” and what the patient wants.

Disclosures:

To choose the right microinvasive glaucoma surgery (MIGS) procedure, glaucoma specialists must consider several questions, according to Brian A. Francis, MD, MS.

Among these questions:
> Is there a coexistent cataract?
> What is the diagnosis?
> What is the anatomy?
> What is the target IOP?
> What medications can the patient use?
> What is the patient’s preference and lifestyle?

Glaucoma surgeries can be categorized based on one of four mechanisms of action, according to Dr. Francis, professor of ophthalmology and holder of the Stieger Endowed Chair at the Doheny Eye Institute and Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles (UCLA).

These categories include the trabecular outflow, suprachoroidal outflow, aqueous humor production, and subconjunctival outflow.

Trabecular outflow

Regarding procedures that target trabecular outflow, surgeons can choose Schlemm’s canal dilation, trabecular stents, or trabecular removal with trabeculotomy/ goniotomy. Methods of Schlemm’s canal dilation-which can be done with or without cataract extraction (CE)-include ab interno canaloplasty, a 360° treatment, and viscodilation of Schlemm’s canal with a catheter. This can be accomplished with Visco360 and the Omni procedures (Sight Sciences).

The iStents (generation 1 and 2; Glaukos) and the Hydrus Microstent (Ivantis) are implants that target trabecular outflow. This mechanism can also be approached via Schlemm’s canal unroofing procedures. The technique can be performed with or without cataract extraction, and it can treat a greater amount of the angle.

For 180° of trabecular removal, surgeons can consider the Trabectome or Goniotome (NeoMedix) or the Kahook Dual Blade (New World Medical). Gonioscopy-assisted transluminal trabeculotomy can be used to treat 360°, as can the Trab360 (Sight Sciences) and Omni procedures.

Suprachoroidal outflow

Procedures that target suprachoroidal outflow are combined with CE. They make use of the suprachoroidal space and uveoscleral outflow. The withdrawn Cypass (Alcon Laboratories) is one such device. Currently, the iStent Supra (Glaukos) is under FDA investigation.

Aqueous humor production

Endoscopic cyclophotocoagulation (ECP) targets aqueous humor production, and the technique is targeted and titratable, Dr. Francis noted. It can be done with or without cataract surgery and is performed via anterior or pars plana approaches. It is useful in mild glaucoma as well as ultra-refractory conditions (ECP-plus or combined with other treatments).

The endoscope is useful in other surgical applications to view intraocular anatomy and pathology, he added. Transscleral cytophotocoagulation or micropulse (subthreshold) laser can also be used, according to Dr. Francis.

Subconjunctival outflow

“I consider subconjunctival outflow procedures as less invasive, not microinvasive, because they do produce a bleb and we use mitomycin,” Dr. Francis said.

These are designed to lower IOP similar to traditional filtration such  as trabeculectomy or aqueous tube shunt, but with lower complication rates. These include the ab interno approach (XEN Gel Stent, Allergan) and the ab externo approach with the investigational glaucoma drainage system (InnFocus Micro Shunt, Santen; not yet FDA approved).

Back to the key questions

Is there a cataract?

The MIGS procedures that are FDA approved in conjunction with cataract extraction are the iStent, iStent inject, and the Hydrus.

“In patients on multiple medications, we should consider MIGS along with cataract extraction even if the patient is well controlled to reduce the medication burden,” according to Dr. Francis.

Trabecular MIGS without a device is an option independent of cataract status. Angle-closure glaucoma may improve with cataract extraction alone, he noted. Because ECP is difficult in a phakic eye, it must be performed with cataract surgery or in pseudophakes, Dr. Francis noted.

Diagnosis and anatomy

In primary and secondary open-angle glaucomas, all procedures are on the table, Dr. Francis said.

“In exfoliation glaucoma trabecular outflow is the main problem, so do a procedure that targets meshwork like a stent or removal.”

The same is true of pigmentary glaucoma. In a narrow angle, glaucoma intervention should be combined with cataract extraction if possible, and caution should be exercised with implants.

“In chronic-angle closure, you can consider MIGS plus goniosynechialysis or aqueous inflow or subconjunctival procedures,” Dr. Francis noted.

Target IOP

In Dr. Francis’ experience, angle procedures result in IOPs in the 14 to 17 mm Hg range, suprachoroidal, a 13 to 15 mm Hg range, aqueous inflow procedures can achieve a 30% reduction, and subconjunctival filtration results in pressures 10 to 14 mm Hg.

“Do not forget that procedures can be combined for greater efficacy in patients with more advanced disease in need for lower target IOPs,” he said. “Patients intolerant to medications also require more aggressive treatments.”

Conclusion

Dr. Francis said he believes that glaucoma surgeons should have at least two or more procedures with different mechanisms of action in their tool kit-techniques that have options for phakic and pseudophakic patients.

“Trabecular outflow procedures are usually first line,” Dr. Francis said. “Aqueous inflow procedures are versatile.”

He said that surgeons should think about combining procedures and always know what they want to accomplish for each patient, based on what the eye is “giving you” and what the patient wants.

Brian A. Francis, MD, MS
E: bfrancis@doheny.org
This article was adapted from Dr. Francis’ presentation during Glaucoma Subspecialty Day at the 2018 meeting of the American Academy of Ophthalmology. He is a speaker for Alcon Laboratories, Allergan, Diopsys, and Innfocus, and is a consultant to Allergan, Bausch + Lomb, Diopsys, Endo Optiks, Glaukos, and NeoMedix.

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