PAUL implant: Good IOP lowering, fewer complications compared with Baerveldt device

The PAUL device was designed to circumvent the shortcomings of the Baerveldt device, Dr Weber explained. Image credit: ©ING Studio 1985 – stock.adobe.com

German investigators, led by first author Constance Weber, MD, reported that the results at 1 year achieved with implantation of the PAUL Glaucoma Implant (Advanced Ophthalmic Innovations), a glaucoma drainage device, resulted in lowering of intraocular pressure (IOP) levels to values that were similar to those achieved with the Baerveldt Glaucoma Implant (Johnson & Johnson). In addition, the PAUL device was associated with lower complication rates postoperatively.¹

The Baerveldt Glaucoma Implant is currently one of the most popular IOP-lowering implants used to treat refractory glaucoma. However, Dr Weber explained, the Baerveldt device also is associated with “a higher rate of postoperative hypotony, which can result in complications such as choroidal effusion, suprachoroidal hemorrhage, shallow anterior chamber and maculopathy."²

The PAUL device was designed to circumvent the shortcomings of the Baerveldt device. While the two devices have similar plate sizes and neither has a valve, the PAUL device has a tube with a smaller lumen diameter (internal diameter of 0.127 mm and external diameter of 0.467 mm).

Dr Weber and colleagues from the Department of Ophthalmology, University of Bonn, Bonn, Germany, undertook a retrospective review of patients undergoing implantation of the PAUL Glaucoma Implant at the University Eye Hospital Bonn, from April 2021 to September 2021. The researchers gauged the qualified and complete success rates based on 4 IOP thresholds: criterion A, IOP of 21 mm Hg or lower; criterion B, IOP of 18 mm Hg or lower; criterion C, IOP of 15 mm Hg or lower; criterion D, IOP of 12 mm Hg or lower.

They also performed an intraluminal stenting technique using a polypropylene (Prolene) thread with the goal of preventing hypotony from developing in the early postoperative period.

PAUL device results

The study included 45 eyes of 41 patients, 40 of whom were Caucasian and one was Southeast Asian. The mean patient age was 66.4 years (range, 18–89 years). Most patients had either chronic open-angle glaucoma (21 eyes, 46.7%) or secondary glaucoma (11 eyes, 24.4%); 29 eyes (64.4%) had undergone a previous glaucoma surgery and six eyes (13.3%) previously had a pars plana vitrectomy, investigators reported.

Dr Weber reported the respective qualified and complete success rates (95% CIs) for the various criteria:

Implantation of the device resulted in marked reductions in the IOPs. The authors reported a mean IOP decrease from 26.1 mm Hg (range, 7–48 mm Hg) to 12.0 mm Hg (range, 3–24 mm Hg) (reduction of 48.83%) at 12 months. Along with the IOP reduction was a reduction in the number of IOP-lowering drugs needed to control the IOP from 3.4 (range, 1–5) to 0.3 (range, 0–3) and 0.5 (0–3) at the 6- and 12-months time points, respectively.

Regarding complications, substantial hypotony with shallowing of the anterior chamber developed in 1 eye (2.2%) and a viscoelastic agent was injected. Choroidal detachments due to hypotony developed in four eyes (8.9%) and resolved without intervention after 6 weeks.

Tubal exposure was another complication that developed in three patients (6.7%) who required conjunctival revision with an additional pericardial patch graft.

The intraluminal Prolene stent was removed in 19 eyes (42.2%) after a mean of 8.4 months (range, 2–12 months). The mean IOP before the removal was 21.9 mm Hg (range, 12–38 mm Hg) and decreased to 11.3 mm Hg (range, 6–16 mm Hg).

In commenting on the results of the study, the investigators said, “Our results showed that the PAUL Glaucoma Implant is an effective glaucoma drainage device that provides effective IOP lowering, similar to that achieved with the Baerveldt Glaucoma Implant, but with lower rates of complications, especially with regard to postoperative hypotony.”

They continued, “The use of an intraluminal Prolene stent helps reduce the rate of postoperative hypotony while also allowing immediate aqueous outflow. Further IOP lowering without an additional procedure is then made possible by removal of this Prolene suture [with the patient seated at] the slit-lamp later in the postoperative course. The latter may well be the reason for a significant reduction in the number for postoperative glaucoma medications when compared to
other glaucoma drainage devices."

References

1. Dr Weber C, Hundertmark S, Liegl R, et al. Clinical outcomes of the PAUL® glaucoma implant: One-year results. Clin Exp Ophthalmol. https://doi.org/10.1111/ceo.14235

2. Sharkawi E, Artes PH, Oleszczuk JD, et al. Systematic occlusion of shunts: control of early postoperative IOP and Hypotony-related complications following glaucoma shunt surgery. J Glaucoma. 2016;25:54-61.

Constance Weber, MD | E: constance.weber@ukbonn.de

Weber is from the Department of Ophthalmology, University of Bonn, Bonn, Germany. She has no financial interest in this subject matter.