Optical coherence tomography (OCT) is frequently used in preoperative diagnostics. However, one of the key challenges of ophthalmic surgery is visualizing and evaluating anterior-segment structures intraoperatively. When using OCT and a traditional microscope during glaucoma surgery, visualizing the anterior-segment angle, trabecular meshwork, Schlemm’s canal, or the collector channels can be challenging. Visualizing these structures in a more detailed fashion is beneficial to assess the quality of the eye’s structures and select the appropriate surgical procedure, to select the ideal location for stent placement, and to confirm whether surgical treatment has been successfully performed immediately after the surgical treatment. In this article, I will describe my experience integrating intraoperative OCT (iOCT) coupled with a digital 3D microscope (Zeiss Artevo 800; Carl Zeiss, Figure 1) into my workflow, including how it impacts my decision-making and how it improves efficiency in my personal experience with surgical glaucoma procedures.

The Best Operation for the Patient

The first step in initiating glaucoma procedures is to determine which procedure is best suited for the patient. A digital microscope provides stereoscopic 3D images on a heads-up display, which allows a real-time clear view of the surgery for the surgeon and the surgical team. The surgeon can observe the flow through collector system vessels at the time of surgery, as well as visualize any existing scarring in the area and evaluate the overall health of the collector system. The surgeon can then decide whether to perform a stenting procedure or a bypass procedure. If the collector system appears to be intact, I often perform a trabecular bypass angle procedure utilizing a stent or microstent vs viscodilation of Schlemm’s canal combined with an ab-interno goniotomy. If the flow through the collector system appears scarred down with minimal flow being visualized, then a procedure bypassing the collector system entirely is best: a trabeculectomy, a Xen gel stent implantation (Allergan), a Preserflo Microshunt (Santen), or a tube shunt procedure. These procedures can be performed beautifully with the improved visualization provided by a digital microscope. This allows for proper device implantation and evaluation of the filtration bleb intraoperatively.

Identify Flow and Proper Placement

Identifying the exact location of collector system vessels allows targeting of the collector system to determine precise stent placement. After I place a stent, I can confirm whether the stent is near the collector channel vs whether it is in the canal as planned. I can ensure that I am dilating both Schlemm’s canal and collector system vessels when placing the stent in the proper position.

Confirm That the Device Is Working

When I implant the device, I can determine whether the device is working by viewing clearly on my display whether it is increasing the flow through the collector system. Amazingly, viscoelastic can be easily visualized dilating even the distal collector system. Because there is a possibility with gel stent implantation that the stent can become blocked by Tenon tissue, an integrated iOCT and digital 3D microscope can confirm this assessment immediately and correct it. I can watch the fluid go into the bleb and I can tell whether the stent lumen is potentially occluded. An intra-Tenon stent placement will likely result in stent failure over time. I can ensure either subconjunctival or sub-Tenon stent placement even when visualization is poor through areas obscured by blood, and patient outcomes are optimized. Proper visualization during these types of procedures helps surgeons avoid tube occlusion and ensure proper tube shunt placement within the anterior-chamber angle as well. This ensures that tubes are not too close to the corneal endothelium as well, which can ultimately prevent late corneal decompensation.

Conclusion

Integrating a digital 3D microscope with iOCT into my workflow adds to the precision of glaucoma surgery and ultimately positively impacts surgical outcomes in my experience. With practice, I believe clinicians will utilize this incredible technology in surgical decision-making as well. For example, collector system flow can even be assessed both before and after cataract surgery in patients with angle surgery. It is possible that additional angle surgery may be deemed unnecessary in the future. Other anterior-segment applications such as evaluating IOL positioning and corneal health may also provide information to surgeons intraoperatively that will ultimately improve patient visual outcomes. Over the years, clinicians have often lamented the need for these types of diagnostic technologies. I truly believe that the days of simply randomly selecting glaucoma procedures and performing procedures where the ultimate location of the stents could be questioned may soon be behind us, due to the recent availability of this truly groundbreaking technology. GP

Steven Vold, MD, is a glaucoma specialist at Vold Vision in Bentonville, Arkansas. Dr. Vold reports consultancy to Zeiss and Sight Sciences. Reach him at svold@voldvision.com.