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

Importance This study provides results of a treatment option for patients with failed primary glaucoma drainage device Background To describe and evaluate the long term intraocular pressure (IOP) control and complications of a new technique joining a second glaucoma drainage device (GDD) directly to an existing GDD: termed “piggyback drainage”. Design A retrospective, interventional cohort study Participants 18 eyes of 17 patients who underwent piggyback drainage between 2004 and 2013 inclusive. All patients had prior GDD with uncontrolled IOP Methods The piggyback technique involved suturing a Baerveldt (250 mm or 350 mm) or Molteno3 GDD to an unused scleral quadrant and connecting the silicone tube to the primary plate bleb. Main Outcome Measures Failure of IOP control defined as an IOP greater than 21 mmHg on maximal therapy on two separate occasions or further intervention to control IOP Results The IOP was controlled in seven eyes (39%) at last follow up with a mean follow up time of 74.2 months. The mean preoperative IOP was 27.1 mmHg (95% CI 23.8 – 30.3) compared to 18.4 mmHg (95% CI 13.9 – 22.8) at last follow up. The mean time to failure was 57.1 months (95% CI 32.2 – 82) and mean time to further surgery was 72.3 months (95% CI 49.9 – 94.7). Lower preoperative IOP was associated with longer duration of IOP control (p = 0.048). If the IOP was controlled over 2 years, it continued to be controlled over the long term. Two eyes (11%) experienced corneal decompensation. Conclusions and Relevance Piggyback drainage represents a viable surgical alternative for the treatment of patients with severe glaucoma with failing primary GDD, particularly in those at high risk of corneal decompensation.