- Design
- Retrospective cohort
- Population
- 186 eyes after failed trabeculectomy (94 repeat trabeculectomy, 92 Ahmed valve)
- Primary outcome
- Visual field progression by ≥2 methods
- Effect
- 31% vs 35% (P = 0.6); peak IOP +11% risk per mmHg
A retrospective US cohort compared 94 eyes having repeat trabeculectomy and 92 having Ahmed valve implantation after a failed first trabeculectomy, with at least four post-operative fields and two years of follow-up.
Field progression by two or more methods occurred in 31% after trabeculectomy and 35% after Ahmed valve (P = 0.6). Trabeculectomy achieved lower pressure on fewer drops, and in eyes with enough prior fields it slowed progression more relative to the pre-operative rate (P = 0.03). Each mmHg of post-operative peak IOP raised the risk of field loss by 11%.
Many surgeons move straight to a tube after a failed trabeculectomy. This suggests repeat trabeculectomy at a new or the same site deserves consideration, particularly where a low pressure target is needed. Surgeon choice, not randomisation, decided the procedure.
- Consider repeat trabeculectomy, not only a tube, after a failed first trabeculectomy.
- Favour trabeculectomy when a low target pressure is needed.
- Monitor for pressure spikes early after either operation.
- Discuss risks of bleb-related infection in the choice.
Why it matters
It challenges the reflex to move to a tube after one failed filter.
Don't overread it
Retrospective and non-randomised; it shows repeat trabeculectomy is reasonable, not that it is better.
The statistics, in plain English
Progression rates of 31% and 35% are not significantly different. The before-and-after comparison favouring trabeculectomy used only the subset with enough pre-operative fields, which weakens it.
Read the rest in the app
You have read your two free briefings this month. The app carries all 27 specialties, every morning, free — and this finding is waiting in it.
Scan to keep reading on your phone. No account needed to start.
Tomorrow morning, before your first patient
One edition a day for ophthalmology, written by the desk, every claim tied to its paper. Six minutes.
Get the app — free