Dr M Rayside, T Khanam, J Rawstron, S Kain, A Giubilato, WH Morgan
Implanting a second glaucoma drainage device into the anterior chamber may carry a signifi-cant risk of corneal decompensation. We evaluated the outcome of joining a second glaucoma drainage device (piggyback) directly to an existing Baerveldt or Molteno plate. To our knowledge, long-term evalua-tion of this procedure has not been previously published.
A retrospective non-comparative interven-tional study of 15 eyes (14 patients) with refractory glaucoma, who underwent piggyback drainage on existing Baerveldt or Molteno tubes by three surgeons. Main outcome measures were success or failure, dura-tion of successful intraocular pressure (IOP) control, and complications. Failure was defined as IOP > 21 mmHg or further glaucoma surgery.
Three of the piggyback devices remained successful at time of last follow-up. Mean follow-up was 47 months. In one of these cases the indication was corneal decompensation, and the subsequent corneal transplant has survived well for more than 5 years. Mean survival time for those piggyback tubes deemed to have failed was 21 months. This compares to a mean survival time of 67 months for the original drainage device in the corresponding patients. Signifi-cant complications of the piggyback procedure were seen in two patients (vitreous plugging, ciliary block glaucoma).
Long-term follow-up of 15 piggyback tubes shows a 20% survival rate. In one case there appears to have been a benefit for corneal transplant survival. Complications were seen in 13% of cases.