Influence of the optical axis-to-target view angle on endoscopic task performance

Abstract

Background: The location of the optical port and the choice of endoscope determine the angle subtended between the optical axis of the endoscope and the plane of the operation target: the optical axis-to-target view (OATV) angle. The aim of the study was to investigate the influence OATV angle on endoscopic task performance.

Methods: The Dundee Endoscopic Psychomotor Tester was used for objective assessment of endoscopic task performance. Ten surgeons carried out a standard task with the optical axis of the endoscope subtending 90°, 75°, 60° and 45° to the target surface. Each subject underwent three test sessions. Each session consisted of one run with each of the OATV angles in a random order. The outcome measures were the errors rate, the execution time, and the force applied on the target.

Results: The 90° OATV angle had the best accuracy, the shortest execution time, and the lowest force applied on the back plate. The errors rate increased from 17% with the 90° OATV angle to 79% with the 45° angle. There was a significant increase in execution time and force with the decrease in the OATV angle (p < 0.0001).

Conclusions: The best task performance is obtained when the optical axis of the endoscope is perpendicular to the target plane.