Novel Surgical Technique – Achieving Optimal Outcomes With Preserflo Microshunt Scleral Fixation

To describe two novel surgical techniques developed for Preserflo microshunt fixation: box mattress suture fixation (1) and external superficial scleral tunnel fixation (2). 

To demonstrate the importance of Preserflo microshunt fixation in preventing occlusion and displacement, compared to conventional non-fixation methods.

Two experienced surgeons from two centres (AK, OK), developed independent methods of Preserflo fixation. Procedures were performed by multiple surgeons under supervision from the two senior authors at the Department of Ophthalmology, King's College Hospital and Queen Mary’s Hospital, United Kingdom.

1.Following Ab-externo implantation of the Preserflo microshunt and confirmation of posterior flow, a 9/0 Vicryl suture is passed over the tube to fixate the distal tail of the implant to the sclera to respect the curvature of the globe,to provide insulation from erosion or occlusion.The suture will last until the capsule is formed.
2.After creating the scleral tunnel for the Preserflo and before the needle entry into the AC, a 1mm lamellar blade is redirected 180 degrees backwards and a short ~0.75mm superficial scleral tunnel is fashioned.Once the Preserflo implant has been implanted,the distal portion of the Preserflo implant is passed beneath the scleral bridge,ensuring secure placement and preventing outward misalignment of the implant.

Anterior segment OCT was used to image the Preserflo position on the sclera as well as bleb formation, measuring the distance of the bleb from the sclera (conjunctiva sclera distance - CSD) and the angle between the Preserflo and the sclera (PSA). Both surgical techniques demonstrated minimum PSA and a good bleb morphology, with posterior flow and a reasonable CSD of at least 2mm height. Angle deviation, erosion, tilting or posterior displacement of the tube were noticed in cases where no fixating techniques were used.
The mean post-op IOP was maintained within target on no or significantly less topical medication, with a lower rate of secondary surgical revision. 75% of patients were on no medications postoperatively at 12 months.

The nature of Tenon's fascia may influence the SIBS biocompatible degradation-resistant tube material.Occlusion from overlying Tenon's,especially in young patients with thick tissue, inflammation secondary to shunt displacement and shunt tenting is a concern in bleb-forming surgery and can lead to failure.This can be minimized by opting for Preserflo fixation surgical techniques,potentially avoiding a surgical revision. In an era of excellence and optimizing clinical outcomes, novelty can lead to longer-lasting success rates and better patient outcomes. The scleral suture fixation and scleral bridge fixation techniques are prime examples of where audit, reflection and evolution of surgery have had a positive impact on patients and outcomes.