Goniolens-free guidance systems for ELT: Less proves to be more

(image Credit: AdobeStock/seanzheng)

Reviewed by Michael S. Berlin, MD, MSc, FAAO

Digitally guided systems, which relieve surgeons from using goniolenses, facilitate more accurate and faster performance of minimally invasive glaucoma surgery (MIGS) procedures by more surgeons.

These benefits, in turn, translate to more consistent and better outcomes for both surgeons and patients, according to lead author Michael Berlin.

Berlin is the founder and director of the Glaucoma Institute of Beverly Hills Research Foundation and a clinical professor at the University of California, Los Angeles Stein Eye Institute. Berlin was joined in this research by Brian Simon, MD, and Jonathan Shakibkhou, MD, both from the Glaucoma Institute of Beverly Hills Research Foundation. Simon also is affiliated with the Loyola University Medical Center, Maywood, Illinois.

When performing excimer laser trabeculostomy (ELT), a MIGS procedure, laser channels are created in the trabecular meshwork to facilitate aqueous outflow. When ELT is coupled intraoperatively with endoscopy or with optical coherence tomography (OCT) guidance, the need for goniolens skills is eliminated and the procedure becomes more accurate and reliable, according to Berlin, who was the first to describe ELT, almost 4 decades ago.

Current MIGS limitations and solutions

The biggest limitation is that current MIGS procedures require that surgeons are skilled in the use of the goniolens, making both the creation of laser channels and insertion of stents challenging, he explained. The results can be inconsistent, compromising outcomes for patients with glaucoma.

This limitation also has been problematic in the adoption of MIGS procedures, which currently are performed by less than 50% of cataract surgeons.¹

“The current procedure relies heavily on the experience and judgment of the surgeon,” Berlin noted.

The introduction of guidance systems in conjunction with ELT enhances MIGS usability for a number of reasons, Berlin pointed out, not the least of which is the elimination of the goniolens.

In addition, with ELT there are no foreign body implants and no limitations in the numbers or locations of the outflow channels. The channel placement is enhanced by collector channel imaging, and surgeons have visual confirmation of the surgical maneuvers in real time.

Performing ELT

“ELT is a validated, safe, and effective laser-based MIGS procedure² with proven long-term intraocular pressure–lowering results of over 12 years,” Berlin said. “The procedure is cost-effective and easily titratable.”

The surgical steps in ELT are as follows. First, a 200-μm fiberoptic probe is introduced through a paracentesis to establish contact with the trabecular meshwork and deliver nonthermal 308-nm xenon chloride excimer laser energy to excise the trabecular meshwork, the juxtacanalicular trabecular meshwork, and the inner wall of the Schlemm canal without damaging the outer wall or collector channels.

A major advantage, he emphasized, is that the trabecular meshwork tissue is converted to gas. No scarring or healing response is induced, and the channels that are created remain patent.³ 

“In guided ELT, a real-time image appears in proper relationship to the target and laser probe to guide the surgeon to direct the probe toward the trabecular meshwork precisely overlying [Schlemm] canal,” Berlin explained. “[Two-dimensional]–guided ELT involves an endoscopic image with a real-time display of an endoscopic artificial intelligence–enhanced image; 3D-guided ELT integrates real-time microscopic OCT and fiber-optic OCT images with artificial intelligence–generated augmented reality images which total internal reflection precludes in an unaided microscope view.”

He demonstrated that such guided systems improved the targeting of the Schlemm canal and collector channels enabled optimal placement of ELT channels.

Michael S. Berlin, MD, MSc, FAAO

E: berlin@g.ucla.edu

This article is based on Berlin’s presentation at the 2024 American Society of Cataract and Refractive Surgery Annual Meeting in Boston, Massachusetts. Berlin holds patents on this technology. Simon and Shakibkhou have no financial disclosures to report.

References:

1. More industry news & trends. Market Scope. Accessed May 15, 2024. https://www.market-scope.com/pages/news-archive

2. Berlin MS, Shakibkhou J, Tilakaratna N, Giers U, Groth SL. Eight-year follow-up of excimer laser trabeculostomy alone and combined with phacoemulsification in patients with open-angle glaucoma. J Cataract Refract Surg. 2022;48(7):838-843. doi:10.1097/j.jcrs.0000000000000856

3. Berlin MS, Simon B, Shakibkhou J. Novel endoscopic and OCT-based guidance systems for excimer laser trabeculostomy. Presented at: 2024 American Society of Cataract and Refractive Surgery Annual Meeting; April 5-9, 2024; Boston, MA; Session SPS-219.