Glaucoma drainage devices (GDDs) are being used with increasing frequency in the surgical treatment of glaucoma. Opinions differ regarding the preferred approach when intraocular pressure (IOP) remains uncontrolled after GDD placement despite reinstitution of medical therapy. Needling the bleb over the end plate, capsule excision, cyclophotocoagulation (CPC), and implantation of a second GDD have all been advocated in the setting of primary GDD failure.
Schaefer and colleagues retrospectively evaluated the long-term outcomes of 32 eyes that underwent CPC and 15 eyes that had implantation of a second GDD after failure of an initial GDD. Additional surgical intervention for glaucoma was required in 11 (34%) eyes in the CPC group and nine (60%) eyes in the GDD group. The majority of CPC failures occurred during the first year of follow-up, while the majority of second GDD failures were observed after five years. The mean follow-up after the second procedure was 63 ± 65.8 months in the CPC group and 132 ± 91.8 months in the GDD group.
A randomized clinical trial is needed to definitively answer the question of whether CPC or placement of a second GDD is the preferred treatment when an initial GDD does not provide adequate IOP control
Although no significant differences were noted in the baseline characteristics between the CPC and GDD groups, there may have been other factors that directed the surgeon toward one treatment or the other. Visual acuity, IOP, medical therapy, and failure data are presented at last follow-up. However, this information is not meaningful, given the marked difference in duration of follow-up between the two study groups. Kaplan-Meier survival analysis and outcomes data at one year are also provided, but no statistical comparisons are made between the CPC and GDD groups.
The authors are to be congratulated for adding important information about the management of patients who fail primary GDD implantation. As suggested, a randomized clinical trial is needed to definitively answer the question of whether CPC or placement of a second GDD is the preferred treatment when an initial GDD does not provide adequate IOP control.