Intermediate-term and long-term outcome of piggyback drainage: connecting glaucoma drainage device to a device in-situ for improved intraocular pressure control

Abstract

Importance: This study provides results of a treatment option for patients with failed primary glaucoma drainage device.

Background: The study aimed to describe and evaluate the long-term intraocular pressure control and complications of a new technique joining a second glaucoma drainage device directly to an existing glaucoma drainage device termed 'piggyback drainage'.

Design: This is a retrospective, interventional cohort study.

Participants: Eighteen eyes of 17 patients who underwent piggyback drainage between 2004 and 2013 inclusive have been studied. All patients had prior glaucoma drainage device with uncontrolled intraocular pressure.

Methods: The piggyback technique involved suturing a Baerveldt (250 or 350 mm) or Molteno3 glaucoma drainage device to an unused scleral quadrant and connecting the silicone tube to the primary plate bleb.

Main outcome measures: Failure of intraocular pressure control defined as an intraocular pressure greater than 21 mmHg on maximal therapy on two separate occasions or further intervention to control intraocular pressure.

Results: The intraocular pressure was controlled in seven eyes (39%) at last follow-up with a mean follow-up time of 74.2 months. The mean preoperative intraocular pressure was 27.1 mmHg (95% confidence interval 23.8-30.3) compared with 18.4 mmHg (95% confidence interval 13.9-22.8) at last follow-up. The mean time to failure was 57.1 months (95% confidence interval 32.2-82), and the mean time to further surgery was 72.3 months (95% confidence interval 49.9-94.7). Lower preoperative intraocular pressure was associated with longer duration of intraocular pressure control (P = 0.048). If the intraocular pressure was controlled over 2 years, it continued to be controlled over the long term. Two eyes (11%) experienced corneal decompensation.

Conclusions: Piggyback drainage represents a viable surgical alternative for the treatment of patients with severe glaucoma with failing primary glaucoma drainage device, particularly in those at high risk of corneal decompensation.

Keywords: glaucoma; glaucoma drainage device; glaucoma surgery.