# Clinical and Imaging Outcomes of the Upside‑Down Pars Plana Ahmed Glaucoma Valve Implantation: A Follow‑Up to Our Initial Report

## TL;DR

A new surgical technique for glaucoma using an upside-down valve implant showed long-term effectiveness in reducing eye pressure and maintaining stable bleb structure.

## Contribution

The upside-down AGV technique via the pars plana is proposed as a novel approach to improve long-term outcomes in refractory glaucoma.

## Key findings

- Sustained intraocular pressure reduction was observed over 66 months.
- Orbital MRI showed preserved double-layered bleb morphology in two eyes.
- No persistent hypotony or tube exposure occurred despite no antifibrotic agents.

## Abstract

Introduction: Tube shunts are essential for refractory glaucoma, yet plate encapsulation can compromise long-term efficacy. We evaluated long-term clinical and imaging outcomes of an “upside-down” Ahmed glaucoma valve (AGV) technique via the pars plana, which may favorably modify bleb architecture.

Methods: This retrospective observational study included 10 eyes from 10 patients who underwent pars plana AGV implantation with the valve plate flipped upside down to direct the drainage port toward the scleral surface. Outcomes included intraocular pressure (IOP), glaucoma medication score, postoperative complications, and corneal endothelial cell density (ECD). Orbital magnetic resonance imaging (MRI) was performed in two eyes to assess bleb morphology.

Results: Mean follow-up was 45.9 ± 24.2 months. Mean preoperative IOP decreased from 35.8 ± 4.4 to 14.9 ± 0.6 mmHg at 66 months (p < 0.05). The glaucoma medication score decreased from 4.6 ± 0.7 to 2.4 ± 0.5 at 42 months (p < 0.05). Transient postoperative hypertension occurred in seven eyes and resolved without surgical intervention. Three patients lost light perception due to retinal ischemia related to the underlying disease. No persistent hypotony or tube exposure was observed. Orbital MRI obtained at approximately six years postoperatively demonstrated preservation of a double-layered peri-endplate bleb configuration in two eyes. The average monthly ECD loss rate was 0.28% ± 0.26%.

Conclusions: The upside-down pars plana AGV technique achieved sustained IOP reduction through 66 months and suggested stable long-term bleb morphology on MRI without adjunctive antifibrotic agents. This approach may be a useful option for complex refractory glaucoma.