Nishani Amerasinghe, Ophthalmic Surgeon at University Hospital Southampton NHS Foundation Trust, has been performing Hydrus® Microstent procedures for over a year and says she is “really impressed at how well my patients are doing.”

Speaking at Alcon’s Hydrus symposium during the European Glaucoma Society Congress in Dublin (June 1–4, 2024), she shared her surgical pearls, ergonomic tips, and step-by-step approach to ensure safe, effective implantation, as well as practical ways to identify and resolve intra-operative problems in real time.

Achieving optimal visualisation

“The key to perfect implantation with any MIGS, of course, is good visualisation,” Amerasinghe began. She went on to summarise her gonio “ergonomic pearls” for optimising the surgical view:

• Adopt a temporal approach.

• Tilt the microscope and the patient’s head to achieve a 35–45° angle.

• Set the microscope rotation to around 30–40°.

• Lightly balance the gonio lens on the eye using an OVD coupling agent, ensuring it does not press on the cannula.

• Increase magnification for the clearest possible image.

These adjustments, she explained, allow the surgeon to achieve and maintain the best possible view of the trabecular meshwork – the starting point for any successful Hydrus procedure.

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Four surgical steps

Amerasinghe outlined the four principal stages of Hydrus implantation:

1. Incision – Create the incision three to four clock hours away from the intended implantation site.

2. Engagement – Incise the trabecular meshwork with the cannula, then tilt the cannula 15–20° anteriorly to engage the tissue correctly.

3. Implantation – With the cannula tip up and engaged, advance the first scaffold window, align the cannula, and then guide the rest of the Hydrus through the canal. “You know exactly when you’re in the right plane,” she explained.

4. Confirmation – Verify that 50–75% of the transition zone is covered by trabecular meshwork, with the inlet visible in the anterior chamber.

“When you follow these four main surgical steps meticulously, it’s very easy to insert the Hydrus,” she said, noting that these fundamentals form the basis of consistent success.

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Refined incision technique

Drawing on her faculty experience, Amerasinghe described a preferred nonradial corneal incision technique designed to optimise entry and streamline stent delivery. The incision is made three to four clock hours from the trabecular meshwork entry point, in clear cornea, approximately 1.5 mm in length, and directed toward the trabecular meshwork target.

This approach allows the surgeon to rest the cannula over the cornea before entry to determine the optimal incision site. If desired, the site can be marked with ink for accuracy. The goal, she stressed, is to enter efficiently while maintaining a trajectory that facilitates smooth Hydrus delivery.

Placement verification

Placement confirmation, Amerasinghe emphasised, is a visual process supported by key anatomical cues. Proper positioning is achieved when:

• 50–75% of the transition zone is covered by trabecular meshwork.

• The inlet is visible in the anterior chamber and parallel to the trabecular meshwork.

• The distal tip is observed in the canal.

Additional signs include the appearance of three scaffold windows in the canal and the characteristic “dull” look of the stent when correctly embedded in the trabecular meshwork. Once placement is verified, the viscoelastic is evacuated, the anterior chamber reformed, and the corneal incision hydrated.

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Recognising and resolving problems

Amerasinghe devoted part of her talk to intraoperative problem-solving, noting that the Hydrus offers the advantage of immediate visual feedback, enabling swift correction.

One potential issue is superficial delivery, visible when the stent appears shiny rather than dull. In such cases, the surgeon should recapture the device by reversing the delivery wheel, withdraw it, and reimplant in the correct plane.

Another complication is posterior delivery, often the result of an overly steep or acute cannula approach. This can make advancement difficult, cause excess pressure on the eye, and result in the stent diving too far posteriorly. If identified early, the solution is to retract the device and re position it further downstream from the original incision.

These scenarios, she stressed, illustrate the value of the Hydrus system: “Straight away you can retract and reposition the stent… the confirmation of placement you get is immediate.”

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While there is a learning curve with Hydrus implantation, Amerasinghe reassured the audience that precision and consistency come quickly. “If you’re meticulous with each of the steps, you’ll find actually that the placement is easy… It’s very easy to recite it straight away.”

Amerasinghe also shared her positive experience using the Hydrus with the Ingenuity 3D Visualisation System. This, she said, offers exceptional clarity of the surgical field, aiding both the procedure itself and teaching opportunities.

In closing, Amerasinghe underscored the straightforward nature of Hydrus implantation when performed with good visualisation and adherence to her stepwise technique. “I wouldn’t say it’s a difficult operation at all,” she told delegates. “You know you’re exactly in the right place straight away while you’re operating. And if you’re not… you can deal with that on the table. The confirmation and feedback you get gives you the confidence to do it well.”

With disciplined technique, ergonomic efficiency, and an eye for intraoperative cues, she added, surgeons can approach the Hydrus® Microstent safe in the knowledge that any deviations can be spotted and corrected in real time.

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