Repeat Canaloplasty After IOP Rise
Yes, canaloplasty can be repeated after IOP rises again, provided Schlemm's canal remains intact and undamaged from the previous surgery. This is a viable surgical option that has demonstrated success in clinical practice, though the decision requires careful assessment of canal integrity 1.
Evidence for Repeat Canaloplasty
The feasibility of repeat canaloplasty depends entirely on whether the initial surgery preserved Schlemm's canal anatomy. A case series demonstrated that canaloplasty could be successfully performed in 5 of 6 eyes with previous failed trabeculectomy, achieving mean IOP reduction from 32.2 mmHg preoperatively to 15.4-17.3 mmHg at follow-up 1. The one failure occurred when the canal could not be cannulated for the full 360-degree circumference, requiring conversion to viscocanalostomy 1.
Preoperative Assessment Requirements
Before considering repeat canaloplasty, you must:
- Perform detailed gonioscopy to verify Schlemm's canal remains intact and accessible - this is the critical determining factor for surgical candidacy 1
- Evaluate the extent of peripheral anterior synechiae (PAS) formation that may have developed since the initial surgery 2
- Assess whether the previous canaloplasty was performed ab externo or ab interno, as the surgical approach affects tissue disruption 3
- Document current IOP levels and medication burden to establish baseline for surgical decision-making 1
Alternative Surgical Options
If repeat canaloplasty is not feasible due to canal damage, consider:
- Modified canaloplasty with suprachoroidal drainage - this technique adds uveoscleral outflow enhancement and achieves IOP reductions comparable to trabeculectomy (45-49% reduction) with superior safety profile 4, 5
- Trabeculectomy - remains the most effective IOP-lowering procedure but carries significantly higher complication risk 4
- Cyclodestructive procedures - traditionally reserved for refractory cases, with success rates of 34-94% but risk of vision loss and need for repeat treatment 2
Important Caveats
The primary limitation is anatomical - if the initial canaloplasty or other prior angle surgery damaged Schlemm's canal, repeat canaloplasty becomes technically impossible 1. In such cases, the surgery must be converted to alternative procedures like viscocanalostomy or trabeculectomy 1.
Timing considerations matter - ensure adequate healing from the first procedure and optimize medical management before proceeding with repeat surgery 2. The American Academy of Ophthalmology emphasizes that surgical decisions for refractory glaucoma should involve consultation with glaucoma specialists when management is in question 2.
Modified techniques offer enhanced outcomes - newer canaloplasty modifications with suprachoroidal drainage demonstrate sustained IOP reduction of 45-47% at four years with minimal complications, potentially offering better long-term control than traditional repeat canaloplasty alone 5.