Surgical simulator training reduces operative times in resident surgeons learning phacoemulsification cataract surgery.

PURPOSE: To compare the surgical duration for routine phacoemulsification surgeries in residents with and without virtual simulator training.
METHODS: Retrospective cohort study of operative times of routine phacoemulsification cataract surgeries performed by 29 different third-year residents rotating at one academic institution. One group underwent mandatory virtual cataract surgery simulator training (SIM) in their second year of residency before starting surgeries while the other group did not undergo any simulator training (NOSIM). Outcomes measured were comparative surgical times and vitreous loss rates between groups in their third year of residency.
RESULTS: 722 surgeries were included. Surgeries in the SIM group were on average 6.7 min (min) shorter compared to the NOSIM group (P = 0.0001). Although both groups required less time for surgery over the course of the academic year, regression analysis showed that NOSIM group residents overall required 17% longer time for an uncomplicated clear corneal phacoemulsification surgery (incidence rate ratio 1.17; p = 0.0001). In the final month of their residency residents in the SIM group (32.2 ± 3 min) were 9 min faster than NOSIM peers (41.2 ± 3 min mean ± SE; p = 0.02). Vitreous loss rates were 1.4% in the SIM group and 3.6% in the NOSIM group (p = 0.06). CONCLUSION AND IMPORTANCE: Early and continuous implementation of mandatory virtual simulator surgical training before starting intraocular surgeries significantly decreases operative times in third year residents learning phacoemulsification compared to non-simulator trained peers.

Introduction

In recent years virtual cataract surgery simulators have become available providing the beginning surgeon with a realistic training environment that allows the trainee to develop fine motor control movements, practice all the steps of phacoemulsification cataract surgery, and also to remediate weak points of past surgical cases during their surgical rotations. Previous reports have shown that virtual cataract surgery simulator training for beginning surgeons reduced phacoemulsification times and complication rates during cataract surgery.1, 2, 3 In a recent study operating room performance after proficiency-based simulator training improved significantly in beginning (32%) and intermediate surgeons (38%). While surgical quality and safety are essential in surgical education, operating room efficiency is also a key element for successful surgeons. Previously, a time-based study of the first fifty surgical cases in simulator and non-simulator groups showed that time was not significantly affected by simulator training in beginning and intermediate surgeons, although a difference was noted after 25 surgeries. The goal of this study was to investigate surgical time length in simulator and non-simulator-trained surgeons in their final year of residency. As we will describe in the following, we find significant improvement in surgical times from simulator training.

Methods

The Institutional Review Board approved this retrospective cohort study at our institution. Each group consisted of third year ophthalmology residents (PGY4) in their final year of residency, who rotated through our institution as second year residents (PGY3) and returned for another rotation in their final year (PGY4). All routine cataract surgeries were performed with a clear corneal incision technique with the divide and conquer phacoemulsification approach. All residents received supplementary cataract surgery training consisting of a wet-lab at the beginning of each academic year, weekly lectures during the 3-month rotation at our institution on surgical technique and management of complications of phacoemulsification. Second year resident surgical times were not included because a scleral tunnel surgical wound technique was used in those surgeries and comparison of surgical times was therefore not possible.

Surgeries were divided into two groups: 1. No simulator group (NOSIM), which included surgeries performed between September 2009 and December 2012 by third-year residents who had no access to surgical simulator training and 2. Simulator curriculum group (SIM), which included surgeries performed between July 2013 and December 2017 by third-year residents who underwent mandatory surgical simulator training (EyeSI, VRtech, Mannheim, Germany) starting during the second year of their residency before they performed their first 12–20 surgical cases. The required training modules A and B of the EyeSI system for the second year residents included anterior chamber navigation (6 modules), intracapsular navigation (6 modules), bimanual navigation (8 modules), instrument handling (6 modules), navigation and instruments (8 submodules), capsulorhexis (12 modules), intracapsular tissue (6 modules), stop and chop (4 modules) and intraocular lens insertion (4 modules). To successfully complete one module the trainee needed to score a certain amount of points while performing the same task on three consecutive attempts. Otherwise the trainee had to restart that submodule over again. This accounted for the total successful completion of 144 exercises. SIM group residents had then unlimited access to the simulator throughout the remainder of their residency. Returning third year residents in the SIM group had access to the surgical simulator for voluntary and unsupervised training.

Outcomes measured were surgical times defined in minutes from incision to speculum removal, and incidence of vitreous loss.

Statistical analysis

Associations between continuous variables were done using two samples t-tests. Associations between categorical variables were calculated using the chi-square or Fishers Exact Test. Regression analysis of surgical time between groups was calculated with a negative binomial regression model. Statistical significance was considered with P < 0.05.

Results

A total of 722 routine phacoemulsification cases (SIM group n = 358 surgeries, NOSIM group n = 364) performed by 29 senior resident surgeons (PGY4) on the same phacoemulsification platform (Alcon Infinity, Ft. Worth, Texas) were included.

The SIM group consists of data from 15 third year residents, who completed the mandatory simulator training during their second year of residency prior to starting live cataract surgery and who also returned to our institution as third-year residents. In the NOSIM group 14 third-year residents were included who also rotated through our facility as second and then third-year residents, but had no access to the surgical simulator. Instead they had access to a surgical microscope for voluntary suture practicing.

During their second year residents trained an average of 496 min (min) (range: 413–577) on the surgical simulator before and during their rotation. Returning third-year (PGY-4) residents logged an average of 333 min (range: 250–450) training time.

SIM group residents performed on average 23 surgeries per three-month rotation and NOSIM residents performed 26 surgeries. This average number of two to three weekly cases for senior residents (PGY4) is consistent throughout the year at our facility, but also at all other rotations and residents graduate with an average of 100 cataract surgeries at the end of their residency. Overall, surgeries in the SIM group were an average of 6.7 min shorter compared to the NOSIM group (P = 0.0001) (Table 1). Both, early in the academic year (July to December), and in the last half of the final year SIM group surgeons were significantly faster compared to NOSIM peers (p = 0.0001; Fig. 1). Before graduation from residency in June, residents in the SIM group performed uncomplicated, clear corneal surgeries (32.2 ± 3 min mean ± SE) on average 9 min faster than NOSIM peers (41.2 ± 3 min mean ± SE; p = 0.02). Prediction of surgical time in uncomplicated clear corneal incision technique surgeries is shown in Fig. 2. Regression analysis of surgical time over the academic year showed that third year residents in the NOSIM group needed 17% longer for an uncomplicated, clear corneal incision phacoemulsification than the SIM group (r = 0.15 SE 0.02, IRR 1.17, 95% CI 0.1–0.19; p = 0.0001).

Table 1

Surgical times in resident surgeons with (SIM) and without (NOSIM) cataract surgery simulator training.

N = Number of Surgeries	SIM group (mean ± SE)	NOSIM group (mean ± SE)	Time difference (minutes)	P*
Total (n = 722)	43.4 ± 0.8 (n = 358)	50.1 ± 0.9 (n = 364)	6.7	0.0001
Uncomplicated (n = 704)	41.6 ± 0.8 (n = 353)	47.7 ± 0.8 (n = 351)	6.1	0.0001

Unpaired T-test. *P < 0.05 considered statistically significant. N = number of surgeries. Uncomplicated surgeries exclude vitreous loss. Surgical simulator training was started one year prior to third year of residency.

Fig. 1

Surgical times of third year residents performing routine cataract surgeries in the first and second half of the academic year. Simulator trained (SIMULATOR) and non-simulator trained (NO SIMULATOR). Mean ± SE (bars). *P < 0.05 statistically significant. Unpaired T test.

Fig. 2

Predicted surgical time based on negative binomial correlation in simulator (SIM, red) and non-simulator (NOSIM, blue) trained third-year (PGY-4) residents performing uncomplicated clear corneal incision phacoemulsification. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

The incidence of posterior capsular tear with vitreous loss was lower in the SIM group (n = 5; 1.4%) compared to the NOSIM group (n = 13; 3.6%), but the difference did not reach statistical significance; p = 0.06). Duration of complicated surgeries with vitreous loss was not different between groups (p = 0.3).

Discussion

To our knowledge, this study is the first to demonstrate a significant reduction in surgical time during uncomplicated routine cataract surgery in simulator trained ophthalmology residents. Previously, Pokroy described that surgical length and posterior capsule ruptures in the first 50 surgeries were not significantly affected by simulator training although times were shorter after the first 25 cases. This observation could be explained by initial adaptation of novice surgeons to the surgical environment and involvement of the attending surgeon completing parts of the procedure. In addition, our study starts with third year residents, who typically have the experience of 20 surgeries at the start of their senior year, and more experience compared to Pokroy's study. Analysis of surgical time by month showed that while both groups made progress in completing the surgery in less time, simulator-trained third year residents had consistently shorter surgical times compared to non-simulator trained peers (Fig. 1, Fig. 2). Although third year residents start the academic year with an experience of approximately 20 cataract surgeries, they begin to perform three to four cases per week and quickly accumulate experience, but have similar numbers throughout the academic year. There is variability with surgical skill levels, but in our study residents rotated every 3 months and the present study includes data from 29 different surgeons. We observed a lower incidence of vitreous loss in simulator-trained residents, but because of the small sample size this difference did not reach statistical significance (p = 0.06). However, a recent larger study including 265 surgeons described a 38% reduction in posterior capsular rupture (PCR) rates (from 4.2% in 2009 to 2.6% in 2015) in first and second year British ophthalmology residents with access to a surgical simulator versus a 3% reduction of PCR rates in non-simulator trained surgeons. These data suggest that simulator training may be beneficial to reduce complication rates in phacoemulsification.

Limitations of our study include its retrospective design with an historical (NOSIM) control group. However, other than the simulator training the surgical curriculum was identical between groups; all residents received the same didactic training, had the same experienced surgical mentors, and the same phacoemulsification platform and instruments. The goal of this study was to compare total surgical times and the retrospective design of the study did not allow us to correlate individual surgical times or specific surgical steps with simulator training times to account for the possibility of more talented surgeons or to compare the module training to surgical step training. We included 29 consecutive residents independently of their surgical adeptness and all 15 residents in the simulator group completed an average of 13.7 h of training which would allow for less talented surgeons to increase their skills. In addition, we observed a low vitreous loss rate in both groups indicating a balanced surgical talent pool in both groups. We found that mandatory simulator training implementation in the second year of residency resulted in significantly shorter surgical times compared to non-simulator trained senior residents. This advantage could be explained by the improved ability to handle instruments intraoperatively, the insight to target areas of experienced surgical problems during simulator training and therefore improve the overall efficiency in live surgery. Further studies are needed to correlate each surgical step with corresponding surgical simulator module training times and to analyze its effect on the efficiency of the management of surgical complications. Teaching cataract surgery is a balance between patient safety, meeting the demands of academic curricula and operating room efficiency. Our data shows that mandatory virtual cataract surgery simulator training can help increase surgical efficiency and safety in senior resident surgeons. An additional benefit of reduced surgical time is greater accessibility to cataract surgery for patients and residents.

Patient consent

This study was IRB approved by our institution and a patient consent waiver was granted. The study complies with HIPPA rules of private health information. This report does not contain any personal information that could lead to the identification of the patient.

Funding

No funding.

Authorship

All authors attest that they meet the current ICMJE criteria for authorship.

Declaration of competing interest

The following authors have nothing to disclose: CL, GS, SS, TM.