An objective evaluation of simulated surgical outcomes among surgical trainees using manual small-incision cataract surgery virtual reality simulator : Indian Journal of Ophthalmology

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Original Article

An objective evaluation of simulated surgical outcomes among surgical trainees using manual small-incision cataract surgery virtual reality simulator

Sankarananthan, R; Prasad, R Senthil; Koshy, Tony Alex; Dharani, Padam; Bacchav, Ashish; Lansingh, Van Charles; Ahiwalay, Chetan; Balagiri, K; Shekhar, Madhu

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Indian Journal of Ophthalmology 70(11):p 4018-4025, November 2022. | DOI: 10.4103/ijo.IJO_1600_22
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Abstract

There are an estimated 31.7 ophthalmologists per million population globally, of whom only less than half perform cataract surgery (mean number, 14.1 ophthalmologists per million population).[1] Taking into consideration the fact that cataract has become one of the leading causes of blindness worldwide, there is an imminent need to train and equip ophthalmologists worldwide to be competent in the field of cataract surgery.

Different training models have been developed and are being used for this very reason which include animal eyeballs, cadaver eyeballs, and inanimate and virtual-reality (VR) models.[2]

Simulation-based training has been in use in various other industries—including the aviation industry—and have now crossed borders into surgical sub-specialties.

Foreign body injuries to the cornea, deep anterior lamellar keratoplasty, goniotomy, various laser procedures, nasolacrimal duct surgery, oculoplastic, retrobulbar injection, scleral indentation, scleral suturing, strabismus surgery, trabecular meshwork surgery, and vitreoretinal procedures are among the many other surgeries in ophthalmology for which simulator models exist.[2]

Retrospective studies have shown that ophthalmologists who have been trained with a virtual reality simulator for cataract surgery have had reduced complication rates during surgery.[34]

There have been several VR simulators that have been developed for phacoemulsification,[5] including the Eyesi Surgical, Phaco Trainer/MicroVisTouch, PhacoVision, and the Phantom Phaco simulator, among others.[678910]

A VR simulator is an invaluable training tool found to have significantly reduced complication rates among novice surgeons when compared to surgeons trained as per the conventional training curriculum.[411]

The HelpMeSee™ Eye Surgery Simulator (HelpMeSee, Inc., New York, USA) is an advanced, virtual reality–based surgical simulator designed for manual small-incision cataract surgery (MSICS) which incorporates the physics model of surgical activities with movements in 3 degrees of freedom and tactile feedback, giving the user a near real world experience [Fig. 1a and b].[11]

F1
Figure 1:
(a) The HelpMeSee Eye Surgery Simulator with the handpieces which transmit the forces and sensation of touch to the fingertips of the operating surgeon. (b) The eyepiece view of the three-dimensional visuals when a trainee is performing capsulorhexis. (c) A screenshot of the sclero-corneal tunnel performance data that the simulator provides after every attempt. Note the scoring system based on the errors and performance data; the simulator can also assess if the attempt was satisfactory or not

These are necessary for surgeons to effectively acquire skills mandatory during live surgery.[11]

Trainers’ evaluations and assessments of trainees’ progress will be subjective and contextual, changing based on factors such as the trainers’ own experience, the trainees’ prior surgical background, and the types of patients on whom the trainees perform surgery.

Data from surgical simulators provide a more objective, standardized basis for assessing a surgeon’s performance.

The purpose of this observational study is to objectively evaluate the MSICS performance of trainees using the HelpMeSee™ simulator in accordance with the simulator’s modules.

Methods

This was a retrospective observational study conducted between December 2021 and May 2022 in a tertiary teaching hospital in Madurai, Tamil Nadu. The study protocol conformed to the Declaration of Helsinki and was approved by the institutional ethics committee.

Participants in the study were various specialty fellows who were posted in microsurgical training for a period of 1 month and who fulfilled the inclusion and exclusion criteria.

The inclusion criteria included trainees who reported performing less than 30 cataract surgeries and those trainees who had completed the minimum number of attempts decided for each step.

The exclusion criteria were those participants with prior experience in the HelpMeSee™ simulation-based training program.

Training in MSICS was standardized according to a well-defined curriculum. This program featured practical oriented theory classes led by a trainer and an independent study through the use of an eBook created by HelpMeSee™.

Trainees would get a detailed description of their live surgery errors which were done daily and which would in turn help them focus on practicing those steps repeatedly on the simulator.

The curriculum included didactic lectures, lab activities, and simulation practice sessions in addition to the simulation training sessions.

During the live surgery, the wet lab, and the simulator practice, each of the trainees were directly supervised by the same trainer.

The simulator had four basic modules in its MSICS simulation-based training course (MSTC): a sclero-corneal tunnel course (SCTC), capsulorhexis and nucleus delivery course (CNDC), cortex removal and intraocular lens (IOL) implantation course (CRIC), and restoration of physical condition course (RPCC).

Trainees were assessed in six major steps in the simulator which included scleral groove, tunnel dissection, keratome entry, capsulorhexis, nucleus delivery, and IOL insertion.

Trainees were designated by the letters A through J.

Each step was assessed as explained below.

Scleral groove

The simulated scleral groove should be between 6.5 and 8.5 mm in length and will get a score of 1. A score of 0 is given if the dimensions lie outside that limit.

The depth of the groove is evaluated by the simulator as true (score of 1) or false (score of 0). Any value that deviates from these will lead to a bad tunnel architecture and an unsatisfactory result.

Uveal prolapse, if present while making a scleral groove, is noted under complication and will receive a score of −3.

The maximum score in this task is 2 and the minimum attainable score is −3.

Tunnel dissection

Length of the tunnel inner lip of 5–7.5 mm and length of tunnel of 3–5 mm are tunnel dimensions necessary for a suitable result with a score of 1 for each. Perforation of outer wall, laceration of outer wall, premature entry, and uveal prolapse are included under complications, each with a score of −3. The maximum attainable score in this task is 2 and minimum score is −12 [Fig. 1c].

Keratome entry

Dimensions of keratome entry should be as follows: length of inner tunnel opening ≥7.5 mm and length of cornea dissected from limbus at 1.7–2.7 mm with a score of 1 each if the candidate performs it satisfactorily. Complications include premature entry, contact with the iris, endothelial contact, contact with the lens, lateral tunnel laceration, and button hole. Nil contact with iris, endothelium, or lens and absence of a premature entry will be awarded a score of 1 while lateral tunnel lacerations and button hole will be given a score of −7 each. The maximum score attainable is 6 and minimum score is −14

Capsulorhexis

Capsulorhexis should have a maximum dimension of at least 6 mm and a minimum dimension of at least 4.5 mm and are awarded a score of 1 if the suitable dimensions are achieved. Contact with iris, endothelial touch, zonular dialysis (ZD), and rhexis runout are included under complications. An absence of iris or endothelial touch and a ZD of less than 10% is awarded a score of 1. ZD of 10%–50% gets a score of 0. ZD of >50% and capsulorhexis runout gets a score of −6. The maximum score in this task is 5 and minimum score is −12.

Nucleus delivery

The nucleus is delivered with wire Vectis. Iris pull and endothelial touch are included under its complications which, if absent during the procedure, will be given a score of 1 each, giving a maximum score of 2 and minimum of 0.

IOL insertion and dialing

IOL insertion is done using a pair of McPherson forceps and dialing by the Sinskey hook. Here, ZD and lost IOL are included in its complications. Occurrence of ZD will be given a score of −2, and if there is no IOL lost during the procedure a score of 1 will be awarded giving a maximum score of 1 and minimum of −2 in this task.

Results

A total of thirty scleral groove attempts were assessed for each candidate. The maximum number of adequate scleral groove length was 23 (B) and minimum was 7 (E, J, and I) [Tables 1-3].

T1
Table 1:
Data of total number of successful attempts in scleral groove, capsulorhexis, nucleus delivery, and IOL implantation in candidates A-D
T2
Table 2:
Data of total number of successful attempts in scleral groove, capsulorhexis, nucleus delivery, and IOL implantation in candidates E-G
T3
Table 3:
Data of total number of successful attempts in scleral groove, capsulorhexis, nucleus delivery, and IOL implantation in candidates H-J

Nine out of ten candidates had inadequate tunnel depths in more than 20 cases.

Complications during scleral groove with uveal prolapse was 11 times by candidate F while others had it occurring less than five times.

Candidate D reached the best satisfactory score in the scleral groove with 13, while the other nine candidates received scores below 10, for a mean satisfactory score of 3.1 ± 4.17 (0–13) across all candidates.

Even though candidate B had satisfactory scleral groove lengths in 23 cases, there were 20 inadequate scleral groove depth attempts, hence reducing the satisfactory score to only eight.

Thirty tunnel dissections were evaluated in all. The length of the inner tunnel limit had variable results with the maximum correct attempts being 21 (A) and minimum being no satisfactory result (I) [Tables 4-6]. It was satisfactory in less than 10 cases in five candidates (B, C, D, I, J) and more than 20 cases by A, whereas length of the tunnel was satisfactory in more than 10 cases by seven candidates (A, E, F, G, H, I, J).

T4
Table 4:
Data of total number of successful attempts in tunnel dissection and keratome entry into AC in candidates A–D
T5
Table 5:
Data of total number of successful attempts in tunnel dissection and keratome entry into AC in candidates E-G
T6
Table 6:
Data of total number of successful attempts in tunnel dissection and keratome entry into AC in candidates H-J

Perforation and laceration of the outer wall were the more common complications during tunnel dissection, with five candidates having 10 or more perforation of the tunnel outer wall (B, C, F, I, J) and 5 had 10 or more tunnel laceration (B, C, E, G, I). Only two candidates had a total satisfactory tunnel dissection of more than 10 cases (A, F). The mean satisfactory score was 6.8 ± 5.75 (0–17).

Complication like uveal prolapse was seen only in three candidates (E, F, J) and premature entry in four (D, E F, J) in their 30 attempts.

A total of 15 keratome entry were assessed for each candidate [Tables 4-6]. The maximum number of correct lengths of inner tunnel opening after keratome entry was in 13 attempts (A) and 11 attempts (D) and minimum was 1 attempt (J). Only four candidates had a satisfactory attempt in only less than 5 cases and 2 in more than 10 attempts.

The maximum number of correct lengths of corneal distance from limbus was in 21 attempts by candidate A. There were six candidates who had a satisfactory attempt in more than ten cases, three candidates who had a satisfactory attempt between five and ten cases (B, I, J), and one candidate who had a satisfactory attempt in fewer than five cases (G).

In the complications, laceration after keratome entry and button hole occurred only once (J and F, respectively). Premature entry and contact with iris were seen in less than five cases in all candidates with maximum occurrence of four times (D and B, respectively). Contact with lens was observed in fewer than 5% of nine candidates. Endothelial touch was seen a maximum of 14 times (A and J) of which 8 candidates had an endothelial touch in more than 5 attempts. Less than five candidates out of nine had an AC entry that was satisfactory, with a mean value of 1.8 ± 2.57 (0–8).

In the 30 capsulorhexis attempts by each candidate, the maximum capsulorhexis size was satisfactory in less than 10 attempts in three candidates, 11–20 attempts in five candidates, and more than 20 in two candidates. The maximum number of correct attempts was 25 (F) and minimum was 7 (A) [Tables 1-3].

The minimum capsulorhexis size was satisfactory in less than ten attempts in three candidates, 11-20 attempts in six candidates and more than 20 in one candidate, with the maximum number of correct attempts being 27 (D) and minimum being 5 (I, J).

Complications like iris contact, endothelial touch, and capsulorhexis runout occurred in less than or equal to 10 cases in 7, 9, and 10 candidates, respectively.

ZD occurred in less than 10 attempts in five candidates, 11–20 attempts in three candidates, and more than 20 in two candidates.

The mean satisfactory score for capsulorhexis amongst all the candidates was 5.8 ± 7.74 (0–24).

Five attempts of nucleus delivery were assessed [Tables 1-3]. There were no complications noted in five candidates whereas five candidates had iris pull (A, B, F, G, J) and two candidates had endothelial touch (G, J) during nucleus delivery. Five candidates had 100% satisfactory nucleus delivery (C, D, E, H, I) and 1 candidate had no satisfactory nucleus delivery (G).

Five attempts of IOL insertion were assessed for each candidate [Tables 1-3]. None of the trainee surgeons had ZD while 1 instance of lost IOL was seen in candidates B, C, E, F and two by candidates A and G. Four candidates had 100% satisfactory outcomes (D, H, I, J).

On a sub-analysis of the current data, when comparing the candidates’ first half of their attempts to their subsequent second half of their attempts in scleral groove, sclero-corneal tunnel, keratome entry, and capsulorhexis, it was observed that the candidates had an overall improvement in the number of satisfactory attempts.

The mean number of satisfactory attempts in scleral groove was 0.8 ± 1.48 (0–4) in the first 15 attempts and 2.1 ± 2.38 (0–8) in the second half of their attempts with a p value of 0.0016. For sclero-corneal tunnel, it improved from 2.3 ± 2.16 (0–7) to 4.5 ± 3.75 (0–10) with a p value of 0.017. For keratome entry, it improved from 0.6 ± 1.07 (0–3) in the first 8 attempts to 1.4 ± 1.58 (0–5) for cases 9–15 with a p value of 0.045. In Capsulorhexis the improvement was from 1.7 ± 2.50 (0-7) to 4.1 ± 5.34 (0-17) with a p value of 0.011. It was statistically significant in all the four steps.

The mean scores in the second half of the attempts also improved when compared with the first half of the attempts in each of the four aforementioned steps Viz. scleral groove, sclero-corneal tunnel, keratome entry and capsulorhexis with a p value 0.413, 0.024, 0.032, and 0.025, respectively, with all steps reaching reaching statistical significance except scleral groove.

Discussion

Only after adequate deliberate practice with feedback, reflective learning, and a competency outcome assessment benchmarked to appropriate standards should supervised live surgical training on patients begin. There are many examples of a standardized curriculum for residency graduates like the comprehensive residency curriculum and standards established by The International Council of Ophthalmology and The Accreditation Council for Graduate Medical Education and the American Board of Ophthalmology before performing cataract surgery.[1213]

Our study did an objective analysis of the surgical performances of 10 trainees in a simulator and their complications while doing so.

There are several lacunae and untapped potential in the area of research in a VR simulator-based studies.

This study is one of the few or if any which has objectively analyzed the results of the performances by trainee surgeons from the metrics provided by the simulator during their MSICS training course alone.

A direct comparison to their live surgical performances during this training period has not been assessed, as we believe the results could be biased owing to certain confounding factors that the subjects get like added information from textbooks, training videos, meetings, wet lab training, and a surgical instructor who explains the intricacies of surgical technique, whose values would be hard to quantify as evidenced in the study by Naseri and Chang[14] that may contribute to the improvement in trainees’ performance.

The ideal ophthalmic surgery simulator would give learners a virtual eye world that looks and feels like a living eye along with a uniform, complete curriculum. Metrics used during training would be reflective of students’ actual abilities and predictive of their actual performance during surgery on real patients.

Evidence indicates that operative performance improves when introducing VR simulation into the cataract surgery curriculum.[151617]

Capsulorhexis and phaco divide and conquer were previously rated the two most difficult steps in phacoemulsification by trainee surgeons, thus strengthening the usefulness of a simulator-based practice.[18]

VR simulator-based training enhanced performance of capsulorhexis in the wet lab, according to Feudner et al.,[6] although direct transfer to real-world surgeries has yet to be demonstrated.

In our study, the dimensions of capsulorhexis in the simulator were adequate more often than the complication rates resulting in lower satisfactory score. This information had enabled the trainees to perform adequately sized capsulorhexis while mitigating those anticipated complications better during live surgeries.

Similarly, the proportions of the sclero-corneal tunnel and keratome entry into AC were generally superior in their dimensional aspects, but were fraught with complexities and architectural issues, with endothelial touch during AC entry being more common.

Hence a better understanding of the complications that are more prone to occur during surgery are identified and rectified earlier by repeated practice and discussions.

According to retrospective research, access to a VR simulator for cataract surgery training (Eyesi; VR Magic) resulted in a 38.1% reduction in posterior capsular rent (PCR) rates for cataract surgical procedures conducted by junior trainees in the United Kingdom, from 4.2% to 2.6%.[3]

Mandatory simulator training for new US residents resulted in a drop of PCR rates from 4.8% to 2.2% in a retrospective comparison.[4]

According to one study, VR training is more effective than using an animal model,[19] and another study showed only an insignificant difference by training on a VR simulator compared to an inanimate model (silicone eye).[20]

When comparing subsequent performance on an animal or cadaver model, two trials found that training on a VR simulator was superior to no training.[621]

Training surgery students in the operating room increases costs because of increased surgery duration.[222324] Lowry et al.[25] performed a cost analysis that suggested that introduction of a VR simulator in a residency program is associated with cost reductions owing to reduction in surgery time. Operating room time was estimated to cost $10 per minute, without including the price of disposable instruments, anesthetics, and other supplies.

Simulator metrics are a good indicator of general microsurgical skills, as demonstrated by the similar performance by experienced cataract surgeons and vitreoretinal surgeons on the simulator.[2]

Simulation-based learning is unavoidable due to the growing ethical concerns, as traditional patient-based practice is no longer acceptable when there are alternatives.

Overall, candidates who practiced on the HelpMeSee™ MSICS Surgical Simulator found it to be beneficial during their training period, with improved performance after additional practice and timely feedback.

Our study has certain limitations, one being the small sample size as only few subjects had completed the set number of attempts in each step and another being the retrospective design of the study.

Only the last set of the defined number of attempts for each module were included from the trainees and not their entire attempts as there were varied number of total attempts in each module by the different trainees, hence the total number of satisfactory attempts have not been included.

Also, a direct comparison between the outcomes from the simulator with the surgical outcomes has not been assessed in this study and will require further studies to elaborate on those findings.

It is possible that a more thorough knowledge of the correlation between simulator performance and actual surgical outcomes could be attained by the use of a larger, more comprehensive, multi-centric, double-blinded prospective trial.

Conclusion

In conclusion, an ophthalmic VR simulator is one of the many options for training ophthalmic surgeons during the early stages of their surgical careers, along with other training modalities such as wet lab, cadaveric eyes, and inanimate objects, but is likely the best tool to objectively evaluate a surgeon’s performance to date. Practicing on the simulator might also minimize the complication rates and improve the dimensional accuracy of each MSICS phase, which can be validated only by additional research in this field.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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Keywords:

HelpMeSee simulator; MSICS; trainee surgeons; VR simulator

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