Failed glaucoma drainage implant: long-term outcomes of a second glaucoma drainage device versus cyclophotocoagulation

Background/aims To evaluate long-term efficacy of a second glaucoma drainage device (GDD) versus cyclophotocoagulation (CPC) after failure of primary drainage implant. Methods This is a non-randomised, retrospective cohort study. A chart review was conducted of patients who underwent GDD surgery between July 1986 and November 2012 requiring further glaucoma procedures for intraocular pressure (IOP) control. An additional GDD was placed in 15 eyes, while 32 eyes underwent CPC. The main outcome measurement was IOP control and/or time to failure of secondary intervention (IOP >18 mm Hg on two sequential measurements). Results Mean follow-up after the second procedure was 63+/-65.8 months (range 6-254 months) in the CPC group and 132+/-91.8 months (range 12-254 months) in the GDD group. Thirty-four per cent (11/32 eyes) undergoing CPC later required further treatment at a mean of 13.6+/-10.7 months with 10/11(91%) of additional interventions occurring within 2 years. Despite an initially high success rate for IOP control in the first 5 years, eventually 60% (9/15 eyes) that underwent a second tube required additional treatment at a mean of 73.4 months with only 2/9(22%) requiring this within the first 2 years. The risk of visual acuity worsening by 2 Snellen lines or more at 12 months was 5/14 for the GDD group (36%) and 4/23(17%) for the CPC group. Conclusions After failure of an initial drainage implant to control IOP, a sequential tube had a high initial rate of success but a relatively high likelihood of long-term failure, generally after 6 years. Eyes that received CPC tended to fail earlier, often within the first year, but had relatively few late failures.