Face and content validity of a virtual-reality simulator for myringotomy with tube placement

Abstract

Background: Myringotomy with tube insertion can be challenging for junior Otolaryngology residents as it is one of the first microscopic procedures they encounter. The Western myringotomy simulator was developed to allow trainees to practice microscope positioning, myringotomy, and tube placement. This virtual-reality simulator is viewed in stereoscopic 3D, and a haptic device is used to manipulate the digital ear model and surgical tools.

Objective: To assess the face and content validity of the Western myringotomy simulator.

Methods: The myringotomy simulator was integrated with new modules to allow speculum placement, manipulation of an operative microscope, and insertion of the ventilation tube through a deformable tympanic membrane. A questionnaire was developed in consultation with instructing surgeons. Fourteen face validity questions focused on the anatomy of the ear, simulation of the operative microscope, appearance and movement of the surgical instruments, deformation and cutting of the eardrum, and myringotomy tube insertion. Six content validity questions focused on training potential on surgical tasks such as speculum placement, microscope positioning, tool navigation, ear anatomy, myringotomy creation and tube insertion. A total of 12 participants from the Department of Otolaryngology-Head and Neck Surgery were recruited for the study. Prior to completing the questionnaire, participants were oriented to the simulator and given unlimited time to practice until they were comfortable with all of its aspects.

Results: Responses to 12 of the 14 questions on face validity were predominantly positive. One issue of concern was with contact modeling related to tube insertion into the eardrum, and the second was with the movement of the blade and forceps. The former could be resolved by using a higher resolution digital model for the eardrum to improve contact localization. The latter could be resolved by using a higher fidelity haptic device. With regard to content validity, 64% of the responses were positive, 21% were neutral, and 15% were negative.

Conclusions: The Western myringotomy simulator appears to have sufficient face and content validity. Further development with automated metrics and skills transference testing is planned.

Fig. 1

Simulator set up. A user is shown using the Western myringotomy simulator. By moving the handle of the haptic arm, the user controls the movement of a virtual myringotomy blade and forceps. The virtual ear and tools floating under the silver screen mirror are an artistic rendering of what the user would see through the 3D glasses

Fig. 2

Simulator scene shown in 2D. The actual scene would be viewed by the user in stereoscopic 3D. a) View of the speculum and myringotomy blade. b) Magnified views of the tympanic membrane through the speculum (represented by the black circle). The view changes depending on the (i) magnification and (ii) position and tilt of the speculum and microscope. c) Myringotomy d) Tube insertion and splaying of the incision. e) Tube in final position with middle ear visible through the lumen of the tube

Fig. 3

Box plot of the Likert item responses for the two groups of participants. Face validity was assessed in Questions 1–14, and content validity was assessed in Questions 15–20. A response of 4 is neutral, and higher values are more favourable than lower values

Fig. 4

Total number of positive, neutral and negative responses to each question, pooling responses of junior residents and of senior Otolaryngologists. The blue bar indicates the number of positive responses (score ≥ 5), the green bar is the number of neutral responses (score = 4), and the beige bar indicates the number of negative responses (score ≤ 3)

Fig. 5

Representation of the virtual tympanic membrane by a collection of discrete points. The points define the geometry of the tympanic membrane and act as contact detectors with the virtual instruments (myringotomy blade, forceps, and ventilation tube)