[Usability testing of the canal expander - a new implant for canaloplasty].

Background: Canaloplasty is a bleb-independent glaucoma surgery in which Schlemm's canal is dilated with a microcatheter and viscoelastic material, and stretched by a tensioning suture. The suture stent has numerous drawbacks such as the technical challenging implantation, deficient knowledge of proper suture tension, late loosening of the suture, or suture extrusion into the anterior chamber. The Stegmann Canal Expander (SCE) was developed to replace the suture stent and to make canaloplasty easier and more reproducible. The aim of this test was evaluate the usability regarding effectiveness, efficacy, and satisfaction of the implanting ophthalmologist (test person).

Methods: In an experimental setting, the test persons were asked to implant the SCE in human autopsy eyes with a surgically prepared Schlemm's canal by means of surgical instruments and an operating microscope. The standardised test was performed in terms of participant observation with a subsequent opinion survey based on checklist and photographic documentation. Data for a successful handling of the task and qualitative data from the experience of the test person with the product were anonymised, collected and registered in an assessment sheet. The evaluation comprised the aspects of instructions for use, packaging, identification, handling, and implantation of the SCE.

Results: The implantation took 2 to 5 min (mean: 3 min). All questions in the assessment sheet regarding effectiveness, efficacy, and satisfaction (n=35) were answered by all test persons (6/6) with the best category ("completely true"; or "no, no problem").

Conclusions: The usability of the SCE under standardised and experimental conditions regarding effectiveness, efficacy, and satisfaction has been rated as very positive, especially allowing for the fact that some of the ophthalmologists did not have experience in glaucoma surgery or only little experience in ophthalmic surgery.