"Ab Interno" Surgery of the Schlemm's Canal in Postuveitic Glaucoma Patients

Abstract

Background: Patients with uveitis have a higher risk of developing glaucoma not only because of the disease by itself, but also because of the ongoing corticosteroid therapy. The pathogenesis of uveitic glaucoma is characterized by a complex of biochemical and cellular processes, as well as morphological changes in the trabecular meshwork. Treatment of secondary chronic glaucoma is challenging and often requires different approaches and solutions.

Purpose: To present the "ab interno" procedure of the Schlemm's canal (SC) performed with the help of TrabEx+ (MST, Redmond, WA, USA) in postuveitic glaucoma patients.

Methods: The observed group included patients with postuveitic secondary glaucoma, which consisted of 12 pseudophakic patients (12 eyes). Patients are with intraocular pressure higher than 25 mmHg and on maximal local therapy. Due to insufficient conservative control on IOP, surgical solutions are needed. We describe a new, minimally invasive surgical procedure-the technique of the operation, the postoperative results and complications.

Results: We present the achieved intraocular pressure (on the first day, 2 weeks, 1 month, 6, 8 12 and 18 months). The morphology of the trabecular area was demonstrated by gonioscopy. The effects of the therapy on the glaucoma progression, was evaluated with perimetry and OCT.

Discussion: The following procedure is a minimally invasive procedure and provides good control of intraocular pressure. Aqueous veins in the conjunctiva are significantly preserved compared to conventional filtration trabeculectomy. This potentially modulates the physiological outflow pathways by ablating trabeculum strip the cause of increased outflow resistance-the inner wall of the SC.

Conclusion: Removal of the inner wall of the SC, using Trabex+ (MST, Redmond, WA, USA), demonstrates promising results in the selected patients with a minimally invasive nature.

Keywords: Schlemm‘s canal; endoscope; glaucoma surgery; secondary glaucoma.

Figure 1

Represents the visual field of a patient with moderate glaucoma before the surgical procedure.

Figure 2

OCT of the same patient with corresponding arquate defect in the inferior half of the visual field.

Figure 3

Gonioscopy view at 12 months. The area of ablation (yellow arrow) and the area of intact trabeculum (red arrow) are clearly visible.

Figure 4

Visualization of the aqueous veins 12 months after surgery (yellow circle).

Figure 5

Axis “x” time, axis “y” IOP (mmHg).

Figure 6

Box plot presentation of preoperative and postoperative intraocular pressure in mmHg.

Figure 7

Kaplan-Meier survival estimates graph for treatment “success” at latest follow-up (intraocular pressure < 21 mm Hg; intraocular pressure lowering > 20%; no reoperation). The axis “x” shows time and the axis “y” (“cum survival”) shows the IOP after the intervention. As it can be seen from the graph, the IOP remains stable over time.

Figure 8

Visual field after the surgical procedure.

Figure 9

Comparison of OCT before and after the surgical procedure.