Trabeculectomy versus canaloplasty (TVC study) in the treatment of patients with open-angle glaucoma: a prospective randomized clinical trial

Abstract

Purpose: To compare the outcomes of canaloplasty and trabeculectomy in open-angle glaucoma.

Methods: This prospective, randomized clinical trial included 62 patients who randomly received trabeculectomy (n = 32) or canaloplasty (n = 30) and were followed up prospectively for 2 years. Primary endpoint was complete (without medication) and qualified success (with or without medication) defined as an intraocular pressure (IOP) of ≤18 mmHg (definition 1) or IOP ≤21 mmHg and ≥20% IOP reduction (definition 2), IOP ≥5 mmHg, no vision loss and no further glaucoma surgery. Secondary endpoints were the absolute IOP reduction, visual acuity, medication, complications and second surgeries.

Results: Surgical treatment significantly reduced IOP in both groups (p < 0.001). Complete success was achieved in 74.2% and 39.1% (definition 1, p = 0.01), and 67.7% and 39.1% (definition 2, p = 0.04) after 2 years in the trabeculectomy and canaloplasty group, respectively. Mean absolute IOP reduction was 10.8 ± 6.9 mmHg in the trabeculectomy and 9.3 ± 5.7 mmHg in the canaloplasty group after 2 years (p = 0.47). Mean IOP was 11.5 ± 3.4 mmHg in the trabeculectomy and 14.4 ± 4.2 mmHg in the canaloplasty group after 2 years. Following trabeculectomy, complications were more frequent including hypotony (37.5%), choroidal detachment (12.5%) and elevated IOP (25.0%).

Conclusions: Trabeculectomy is associated with a stronger IOP reduction and less need for medication at the cost of a higher rate of complications. If target pressure is attainable by moderate IOP reduction, canaloplasty may be considered for its relative ease of postoperative care and lack of complications.

Keywords: canaloplasty; glaucoma surgery; open-angle glaucoma; trabeculectomy.

Figure 1

Kaplan–Meier survival plot of cumulative probability of complete success. Complete success was defined as intraocular pressure (IOP) reduction to ≤18 mmHg (A) or ≤21 mmHg and ≥20% IOP reduction (B) without glaucoma medication.

Figure 2

Intraocular pressure (IOP) results for canaloplasty and trabeculectomy. IOP significantly dropped to a lower level during follow‐up in both groups (p < 0.001). Overall, IOP was significantly lower in patients undergoing trabeculectomy. Box plots illustrate the median (50th percentile) as a black centre line and the 25th and 75th percentile as the lower and upper hinges of the box, 1.5 IQR as the upper and lower bards. Circles represent minor outliers.

Figure 3

Scatter plot of preoperative and postoperative intraocular pressure (IOP) after 2 years. Each eye is illustrated as a single circle or triangle. The oblique line indicates no change of IOP. Circles or triangles above the oblique line define a higher postoperative IOP. Eyes below the line of 18 or 21 mmHg plus 20% IOP reduction fulfilled criteria of success with or without medication.