Flipped classroom integrated with team-based learning enhances surgical skills in ophthalmology residency training: a randomized controlled trial

ERCT Criteria Breakdown

• Level 1 Criteria

  • C

    Class-level RCT

    • Randomisation was performed at the individual student (resident) level via lottery, not at the class or school level, and no tutoring exception applies.
    • "Twenty participants were randomly divided into an experimental group (n = 10) and a control group (n = 10) using a lottery-based randomization method."
    • Relevant Quotes: 1) "Twenty residents who underwent standardized ophthalmology training at the Affiliated People's Hospital of Ningbo University from January 2026 to March 2026 were enrolled and randomly divided into an experimental group (n = 10) and a control group (n = 10)." (Abstract, p. 1) 2) "This study adopted a controlled experimental design. Twenty participants were randomly divided into an experimental group (n = 10) and a control group (n = 10) using a lottery-based randomization method." (p. 2-3) 3) "The ten residents in the experimental group were randomly divided into two TBL groups, with five residents in each subgroup." (p. 3) Detailed Analysis: The ERCT 'C' criterion requires randomisation of entire classes (or the stronger school level), unless the intervention is one-to-one tutoring or personal teaching. Here, 20 individual residents were the units of randomisation, assigned by lottery into two groups within a single training cohort at one institution. This is student-level (individual) randomisation, not class-level or school-level assignment. Because both groups were drawn from the same resident cohort at the same hospital and taught by the same instructor, there is a genuine risk of contamination that class-level randomisation is designed to prevent. The intervention (flipped classroom + TBL) is a group-based teaching method, not one-to-one tutoring, so the tutoring exception does not apply. Criterion C is not met because randomisation was conducted at the individual student level rather than at the class or school level, and no tutoring exception applies.
  • E

    Exam-based Assessment

    • Outcomes were measured with study-adapted scoring tables rather than a widely recognised standardised exam.
    • "The scoring criteria were adapted from the Zhejiang Provincial Standardized Residency Training Clinical Practice Ability Completion Assessment and the Pterygium Excision Scoring Table for Ophthalmic Surgery."
    • Relevant Quotes: 1) "Before the teaching activities began, all participants completed a theoretical examination on pterygium excision surgery, with the results recorded as pre-training theoretical scores to assess their baseline knowledge." (p. 3) 2) "The scoring criteria were adapted from the Zhejiang Provincial Standardized Residency Training Clinical Practice Ability Completion Assessment and the Pterygium Excision Scoring Table for Ophthalmic Surgery. Learning outcomes were objectively evaluated and recorded using quantitative indicators (Figure 1)." (p. 3) 3) "The pterygium excision scoring table comprised five sections: pre-operative preparation, operative procedure, post-operative handling, operational proficiency, and question answering." (p. 5) 4) "The theoretical examination used in this study consisted of type A and type B questions." (p. 7) Detailed Analysis: Criterion E requires a standardised, widely recognised exam-based assessment that is not custom-built for the study. In this paper, both the theoretical examination and the practical skill assessment used scoring tools that were "adapted from" provincial residency training assessments and a pterygium excision scoring table for the specific purpose of this study. While these tools draw on institutional/provincial materials, they are study-tailored instruments (a pterygium-excision- specific scoring table and an author-composed theoretical exam) rather than an externally administered, nationally standardised exam with established validity and reliability as a recognised test. The instruments are therefore closer to a custom-designed assessment aligned to the intervention content than to an independent standardised exam. Criterion E is not met because the assessments were study-adapted scoring tables and an author-composed exam rather than a recognised standardised exam.
  • T

    Term Duration

    • Outcomes were measured immediately after a short wet-lab training block, well under one academic term, with no term-long follow-up.
    • "only immediate post-training outcomes were assessed, without long-term follow-up."
    • Relevant Quotes: 1) "Theoretical examinations were administered before and after training, practical skill assessments were conducted after training, and a teaching satisfaction questionnaire was administered." (Abstract, p. 1) 2) "after training, all residents completed a theoretical examination on the relevant content, with the results recorded as post-training theoretical assessment scores." (p. 3) 3) "Fourth, only immediate post-training outcomes were assessed, without long-term follow-up. The decay curve for surgical skills typically begins to decline 3-6 months after training." (p. 8) Detailed Analysis: Criterion T requires that primary outcomes be measured at least one full academic term (roughly 3-4 months) after the intervention begins, or that the study insist on term-long follow-up tracking even for a short intervention. Here, the intervention was a short wet-lab training exercise on pterygium excision, and both the theoretical exam and the practical skill assessment were administered immediately at the end of training. The authors explicitly acknowledge that "only immediate post-training outcomes were assessed, without long-term follow-up." The interval from intervention start to outcome measurement is therefore far shorter than one academic term, and there is no term-long tracking. Criterion T is not met because outcomes were measured immediately after a brief training block with no follow-up spanning at least one academic term.
  • D

    Documented Control Group

    • The control group's size, demographics, baseline scores, and business-as-usual treatment are clearly documented.
    • "The mean age of residents in the experimental group and control group was 26.40 ± 1.71 years and 25.50 ± 1.35 years, respectively, with no statistically significant difference (p = 0.209)."
    • Relevant Quotes: 1) "Twenty participants were randomly divided into an experimental group (n = 10) and a control group (n = 10) ... the control group received traditional lecture-based teaching." (p. 2-3) 2) "The mean age of residents in the experimental group and control group was 26.40 ± 1.71 years and 25.50 ± 1.35 years, respectively, with no statistically significant difference (p = 0.209). The sex distribution between the two groups also showed no significant difference (p = 0.303). In the experimental group, nine residents held a master's degree and one held a bachelor's degree; all ten residents in the control group held a master's degree." (p. 4-5) 3) "None of the residents in either group had prior learning experience with pterygium excision surgery. Overall, there were no significant differences between the two groups in baseline characteristics such as age, sex, and educational level." (p. 5) 4) "Pre-training theoretical score (mean ± SD) ... 71.00 ± 8.10" for the control group. (Table 1, p. 6) Detailed Analysis: Criterion D requires clear documentation of the control group's composition, size, baseline characteristics, and the treatment it received. The paper reports the control group's size (n = 10), demographic details (age, sex, educational level), confirms comparability at baseline (no significant differences and no prior pterygium surgery experience), and gives baseline and post-training theoretical scores in Table 1. It also states the control group received traditional lecture-based teaching (business as usual) with matched content, class duration, instruments, consumables, and the same instructor. Criterion D is met because the control group's characteristics, size, baseline data, and treatment are clearly documented.

• Level 2 Criteria

  • S

    School-level RCT

    • Randomisation was at the individual student level within a single institution, not at the school level.
    • "Twenty participants were randomly divided into an experimental group (n = 10) and a control group (n = 10) using a lottery-based randomization method."
    • Relevant Quotes: 1) "Twenty participants were randomly divided into an experimental group (n = 10) and a control group (n = 10) using a lottery-based randomization method." (p. 2-3) 2) "A total of twenty residents who underwent standardized ophthalmology training in the People's Hospital of Ningbo University from January 2026 to March 2026 were selected." (p. 2) 3) "Second, this was a single-center, single-discipline study." (p. 8) Detailed Analysis: Criterion S requires that entire schools (or equivalent implementing units/institutions) be the unit of randomisation. In this study, all participants were residents at a single institution (The Affiliated People's Hospital of Ningbo University), and individual residents were randomised by lottery into two groups. This is a single-center trial with individual-level assignment, so there is no randomisation of multiple schools or institutional units. Criterion S is not met because randomisation occurred at the individual student level within one institution rather than across schools.
  • I

    Independent Conduct

    • The same authors designed and delivered the intervention and conducted the assessments, with no independent or third-party evaluator.
    • "the teacher was the same senior ophthalmologist for both groups, ensuring that all variables except the teaching method were effectively controlled."
    • Relevant Quotes: 1) "All sessions took place in the same wet laboratory, and the teacher was the same senior ophthalmologist for both groups, ensuring that all variables except the teaching method were effectively controlled." (p. 3) 2) "Author contributions: ZW: Conceptualization, Investigation, Methodology, Project administration, Supervision ... JX: Data curation, Formal analysis, Methodology, Validation, Visualization ..." (p. 8) 3) "The author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest." (p. 8) Detailed Analysis: Criterion I requires that the study be conducted independently from those who designed the intervention, typically through an external evaluation team or third-party oversight. Here, the authors conceived, designed, delivered, and assessed the teaching intervention themselves; the instruction was delivered by the same senior ophthalmologist for both arms, and the authors performed the investigation, data curation, and analysis. There is no statement of an independent evaluator, blinded external assessor, or third-party oversight of data collection and analysis. Criterion I is not met because the same team designed, delivered, and evaluated the intervention with no independent conduct or third-party oversight.
  • Y

    Year Duration

    • The intervention and its measurement spanned far less than a full academic year, and criterion T is not met.
    • "only immediate post-training outcomes were assessed, without long-term follow-up."
    • Relevant Quotes: 1) "Theoretical examinations were administered before and after training, practical skill assessments were conducted after training." (Abstract, p. 1) 2) "Fourth, only immediate post-training outcomes were assessed, without long-term follow-up." (p. 8) 3) "Whether the skill memory established by the flipped classroom combined with TBL method is more durable than that from traditional teaching is a question that future research must address." (p. 8) Detailed Analysis: Criterion Y requires that outcomes be measured at least 75% of a full academic year (roughly 9-10 months) after the intervention begins. Per the criterion-specific rule, if criterion T (Term Duration) is not met, then Y cannot be met. Here, the intervention was a short wet-lab training exercise with outcomes assessed immediately afterward, and the authors explicitly note the absence of any long-term follow-up. This is far short of a full academic year. Criterion Y is not met because the study duration and measurement interval were far shorter than an academic year, and criterion T is also not met.
  • B

    Balanced Control Group

    • Both groups were explicitly matched on content, class duration, instruments, consumables, and instructor, and any extra pre-class self-study is integral to the flipped-classroom method being tested.
    • "The two groups were matched for training content, class duration, surgical instruments, and consumables. All sessions took place in the same wet laboratory, and the teacher was the same senior ophthalmologist for both groups."
    • Relevant Quotes: 1) "The two groups were matched for training content, class duration, surgical instruments, and consumables. All sessions took place in the same wet laboratory, and the teacher was the same senior ophthalmologist for both groups, ensuring that all variables except the teaching method were effectively controlled." (p. 3) 2) "Pre-class learning: the teacher provided relevant learning materials to the residents in advance ... Residents were required to complete independent learning before class." (p. 3) 3) "In-class theoretical teaching: the teacher delivered a unified lecture on the theory of pterygium excision surgery ... the remaining class time was allocated for residents to practice independently." (p. 3) Detailed Analysis: Criterion B asks whether intervention and control groups received comparable time, budget, and materials, unless any extra resource is integral to the treatment variable being tested. The paper states that the two groups were explicitly matched on training content, class duration, surgical instruments, consumables, wet-lab setting, and instructor, so in-class time and material resources were equalised. The one structural difference is that the experimental (flipped) group completed pre-class self-study of provided materials and videos, whereas the control group received the theory as an in-class lecture. This pre-class self-study is not a separable, confounding add-on; it is the defining feature of the flipped classroom model that is precisely the treatment variable under investigation (moving knowledge acquisition to the pre-class phase so in-class time can be used for practice). Under the ERCT decision logic, such an integral component does not violate criterion B, and the remaining inputs were matched between groups. Criterion B is met because in-class time, materials, instruments, and instructor were matched across groups, and the only difference (pre-class self-study) is integral to the flipped-classroom method being tested.

• Level 3 Criteria

  • R

    Reproduced

    • No independent replication of this specific study exists; the authors present the flipped-plus-TBL combination as novel and previously lacking.
    • "research on the combined application of flipped classroom and TBL in ophthalmic surgical training is currently lacking."
    • Relevant Quotes: 1) "However, research on the combined application of flipped classroom and TBL in ophthalmic surgical training is currently lacking. Therefore, this study aimed to further evaluate the application value of the flipped classroom combined with TBL method." (p. 2) 2) "Second, this was a single-center, single-discipline study. The teaching effectiveness of this model in other centers or disciplines requires further investigation with broader populations." (p. 8) Detailed Analysis: Criterion R requires independent replication of the specific study by a different research team in a different context, published in a peer-reviewed journal. The authors explicitly frame their combined flipped classroom + TBL application in ophthalmic surgical training as novel and previously lacking, and call for further multi-center validation. While related flipped classroom and TBL studies exist in medical education generally (the paper itself cites such work), none constitutes an independent replication of this specific single-center ophthalmology pterygium surgical-skills trial. Given the article's very recent publication (Frontiers in Medicine, 04 June 2026) and its framing of the combined method as novel, an independent reproduction of this particular study is implausible at this time, and none was identified. Criterion R is not met because no independent replication of this specific study has been conducted.
  • A

    All-subject Exams

    • Only pterygium excision surgical skill and related theory were assessed, and criterion E is not met.
    • "Pterygium excision surgery was selected as the teaching content for this educational study."
    • Relevant Quotes: 1) "Pterygium excision surgery was selected as the teaching content for this educational study." (p. 3) 2) "The pterygium excision scoring table comprised five sections: pre-operative preparation, operative procedure, post-operative handling, operational proficiency, and question answering." (p. 5) Detailed Analysis: Criterion A requires that impact be measured across all main subjects using standardised exam-based assessments, and it has criterion E as a prerequisite. Here, the study assessed only a single, narrow domain (pterygium excision surgical skills plus related theoretical knowledge), not a range of subjects. Moreover, since criterion E was not met (the assessments were study-adapted scoring tables rather than recognised standardised exams), criterion A automatically fails as well. Criterion A is not met because only a single specialised surgical topic was assessed and criterion E is not satisfied.
  • G

    Graduation Tracking

    • There was no follow-up to graduation; only immediate post-training outcomes were measured, and criterion Y is not met.
    • "only immediate post-training outcomes were assessed, without long-term follow-up."
    • Relevant Quotes: 1) "Fourth, only immediate post-training outcomes were assessed, without long-term follow-up." (p. 8) 2) "To address the third and fourth limitations, our research team has developed a proctoring plan for the participants ... This plan involves real patients and is currently under ethical review." (p. 8) Detailed Analysis: Criterion G requires tracking participants through to graduation from their educational stage, and it has criterion Y as a prerequisite. The authors explicitly state that only immediate post-training outcomes were measured, with no long-term follow-up; a longer-term proctoring plan is described only as a future study under ethical review. There is no tracking of residents to the completion/graduation of their standardized training, and no subsequent graduation-tracking publication by the same authors could be identified. Since criterion Y is also not met, criterion G cannot be met. Criterion G is not met because no graduation tracking or long-term follow-up was conducted and criterion Y is not satisfied.
  • P

    Pre-Registered

    • The paper reports ethics approval but provides no pre-registration of the study protocol in any trial registry before data collection.
    • Relevant Quotes: 1) "this study has been approved by the Medical Ethics Committee of the People's Hospital Affiliated to Ningbo University (approval no.: 2026 Scientific Research No. 049)." (p. 2) 2) "The studies involving humans were approved by the Ethics Committee of The Affiliated People's Hospital of Ningbo University." (p. 8) Detailed Analysis: Criterion P requires that the full study protocol be pre-registered in a public registry (e.g., ClinicalTrials.gov, ISRCTN, ChiCTR) before data collection begins, including hypotheses, methods, and planned analyses. The paper reports institutional ethics approval but makes no mention of any trial registration or pre-registered protocol, and provides no registry ID or registration date. Checking the published article on the Frontiers landing page likewise revealed no trial registration identifier. Ethics approval is not equivalent to pre-registration. Criterion P is not met because there is no evidence of a pre-registered protocol in a public registry.