Validity evidence of a new virtual reality simulator for phacoemulsification training in cataract surgery

Abstract

This study aims to assess validity evidence of the new phacoemulsification module of the HelpMeSee [HMS] virtual reality simulator. Conducted at the Ophthalmology Department of Strasbourg University Hospital and Gepromed Education Department, Strasbourg, France, this cross-sectional study divided 20 surgeons into two groups based on their experience over or under 300 cataract surgeries. Surgeons filled out a background survey covering their phacoemulsification experience and prior simulator use before undergoing single-session simulations on the EyeSi [EYS] and HMS simulators. Handgrip strength was measured pre- and post-simulation to evaluate grip fatigue. Afterwards, surgeons rated the perceived realism on a seven-point Likert scale. Participants were predominantly right-handed males, with expert surgeons averaging 44 years and intermediate surgeons 29 years of age. Expert surgeons had completed around 2000 phacoemulsification surgeries compared to 150 by intermediates. Primary outcome was to assess the construct validity of HMS simulator based on the difference in total and modules scores between both groups. Significant performance differences were observed between the two groups, with experts scoring higher. HMS scores were 35.8 ± 1.5 out of 46 points for experts and 27.2 ± 2.3 for intermediates (p = 0.006). For EYS, scores were 405.2 ± 20.3 out of 500 points for experts and 327.8 ± 25.2 for intermediates (p = 0.028). Experts experienced significantly less grip fatigue post-simulation on HMS compared to intermediates. This research evaluates validity evidence of HMS's phacoemulsification modules for the first time. It emphasizes the potential to broaden simulation-based training by targeting diverse populations.

Keywords: Construct validity; EyeSi; Handgrip fatigue; HelpMeSee simulator; Phacoemulsification training; Virtual reality simulation.

Fig. 1

Virtual reality simulators. (A) EyeSi© (EYS) is a computer system with a microscope-like display for 3D visuals. It features a table setup with a mannequin head, a simulated eye, two control pedals for microscope and phacoemulsification operations, and a tactile interface with three ophthalmic probes. (B) HelpMeSee© (HMS) is a virtual reality simulator with tactile feedback, resembling a reclining patient connected to a microscope-shaped screen for 3D visuals. The setup includes a table, a mannequin head with tactile feedback, a single pedal for phacoemulsification control, and a tactile interface with two ophthalmic probes that mimic the surgical instruments.

Fig. 2

Common phacoemulsification modules in both simulators with associated scores. The two virtual reality simulators differ in the modules available. The HelpMeSee (HMS) offers the possibility of practising each stage of phacoemulsification, divided into sub-sequences to practise each gesture separately. The EYS can be used to configure a personalised programme for surgeons wishing to evaluate a complete surgical procedure (excluding incisions and hydrosuture). For this study, we used all the steps common to both simulators, i.e. the complete surgery programme (excluding incisions and hydrosuture) on the HMS and a personalised programme on the EYS. The total scores generated were used as the primary endpoint for statistical evaluation. EYS: EyeSi^® simulator (Haag-Streit, Mannheim, Germany). HMS: HelpMeSee^® simulator (HelpMeSee foundation, New York, United States). *configured: no guiding elements, no weak zonula fibers, initially stained, capsular tension medium.

Fig. 3

Total scores of the participants. As the metrics for the two simulators have different scales, that is, maximum score 46 for HelpMeSee© (HMS) and 500 for EyeSi© (EYS), results are represented on two different graphs. On both simulators, the expert group scored significantly higher than the intermediate group, demonstrating the validity (construct validity) of the latter.

Fig. 4

Scores of the participants by module. A comparison was made between the expert and intermediate groups on each of the modules to assess which modules were the most discriminating between the two groups. As the metrics of the two simulators have different scales, they are represented on two different graphs. (A) Eyesi^® simulator (EYS). The expert group showed a better average for each module. However, only the Phaco Divide & Conquer module showed a significant difference between the scores of the two groups. (B) HelpMeSee^® simulator (HMS). Unlike the EYS, some modules: hydrodissection, nucleus rotation and IOL insertion showed no difference between the two groups. For other modules: grooving, cracking, cortex removal and IOL dialing, the average of the expert group was higher than that of the intermediate group, although the difference was not statistically significant. Finally, two modules proved to be significantly discriminating: capsulorhexis and quadrant removal. ns P > 0.05 * P ≤ 0.05 ** P ≤ 0.01 *** P ≤ 0.001 **** P ≤ 0.0001. IA: irrigation & aspiration for cortex removal

Fig. 5

Results of the satisfaction questionnaires for HelpMeSee^® (HMS) and Eyesi^® (EYS) simulators. All the participants were asked to complete a satisfaction questionnaire on the realism of the simulators after each evaluation session. The two groups gave a broadly similar assessment of the two simulators for all the questions asked, except for hand-microscope co-ordination, where the senior group had more reservations (> 30% difference in satisfaction). The two simulators also elicited the most mixed opinions on the interaction of the instruments with the simulated anatomical elements. On all the questions asked, the opinions given on the EYS simulator were more favourable at the time the study was conducted (Q1 2024). Coordination: hand-microscope coordination for real surgery. Multitasking: multitasking (microscope, hand, pedals, phacoemulsification machine settings). Movement: Movement of the surgical instruments. Depth of focus: Depth of field in binocular vision. Instr. Interaction: Interaction between surgical instruments. Anat. Interaction: Interaction of surgical instruments with simulated anatomical elements. Interface: User-friendly computer interface.