Learning Cataract Surgery: Expected and Unexpected Experience in a Single Center, Single Teacher, Single Surgeon Setting

Cataract remains a prevalent cause of blindness globally, with surgical intervention being the primary treatment modality [1]. While cataract surgery is among the most frequently performed procedures in medicine, mastering its microsurgical techniques poses a significant learning curve [2]. With the impending demographic shift leading to an increased incidence of cataracts, there arises a pressing need to assess and optimize training methodologies [3].

This study investigates the learning behaviour of individual surgeons undergoing cataract surgery training within an ambulatory single-centre, single-teacher framework. Parameters including process times, complication rates, and the result of visual outcomes were analysed to evaluate the efficacy of this educational approach. The findings offer insights into the quality and effectiveness of training strategies in preparing surgeons for proficient cataract surgical practice and have a future impact for the raising demand of the ophthalmology specialists.

Cataract surgeries were conducted in an ambulatory eye clinic, with all procedures performed under local topical anesthesia or analgesic sedation, administered by a board-certified anesthesiologist. A standardized intraoperative protocol was followed, and all surgeries were performed using the manual phacoemulsification technique under the supervision of an experienced ophthalmic surgeon. 

The surgical procedure commenced with corneal access via a 2.5 mm incision, followed by continuous curvilinear capsulorhexis using fine forceps. Lens nucleus fragmentation was typically achieved using the divide-and-conquer technique, after which monomanual irrigation-aspiration was utilized to remove cortical remnants. When feasible, a foldable acrylic intraocular lens (IOL) was implanted within the capsular bag. 

During the initial phase of surgical training, individual procedural steps were systematically isolated, with the supervisor executing all steps preceding the one to be acquired by the trainee. This stepwise approach was implemented progressively until the trainee demonstrated proficiency in each stage, as determined by the supervising surgeon (Table. 1). In addition to hands-on surgical training, practical exercises were performed using porcine eyes and digital surgical simulation technology (Eyesi Surgical Simulator). Following this training phase, the trainee proceeded to perform complete cataract surgeries independently, marking the initiation of outcome analysis.

Table 1: Surgical skills training of the cataract surgeries. Surgical steps and number of procedures, performed by the trainee. 

The results were subsequently compared to those of the supervising surgeon, who had an extensive experience of over 20 years and an annual surgical volume of approximately 700 cataract procedures.

Data collection, statistical analysis, and graphical representation were conducted using Microsoft Excel (Microsoft Corporation, Redmond, USA). Consecutive cases were grouped in increments of 10 surgeries and analyzed using statistical process control (SPC) methodologies. Quality control assessments were performed using Shewhart control charts, a method originally introduced by Walter A. Shewhart in 1924 for industrial quality control applications. These charts were employed to monitor process stability and detect systematic deviations from expected performance within the surgical workflow.

The application of Shewhart control charts allowed for an objective evaluation of process stability by distinguishing systematic errors from inherent random variations in the surgical process. This approach facilitated early identification of deviations from expected performance trends, ensuring continuous quality assurance in the ambulatory cataract surgery setting [4].

A total of 413 surgeries, conducted by two trainee surgeons over a one-year period each, were included in the study. Operator A's learning curve (Figure 1) follows an expected trajectory and can be mathematically described. After approximately 100 independently performed procedures, process times become stable.

Figure 1: Duration of cataract surgeries, shown in consecutive bocks of 10 surgeries. Operator A 

A similar pattern is observed in the analysis of complications (Figure 2), where a stable situation is evident after around 300 procedures. The complication rate stabilizes below 5% after 320 cases.

Figure 2: Complication Rate. Operator A 

In contrast, Operator B exhibits a different pattern. The variation in process time duration demonstrates oscillatory dispersion (Figure 3), while complications show a more continuous increase across cases, stabilizing at 4% after 100 cases (Figure 4).

Figure 3: Duration of Cataract surgeries, shown in consecutive cases of 10. Operator B

Figure 4: Complication Rate. Operator B 

Both operators show no differences in visual acuity changes (Figure 5). Thus, no discernible learning or experience curve is evident in this aspect.

Figure 5: Visual Improvement after 4 Weeks. Blue column – Operator A, orange – Surgeon B. 

The data of 100 cases, performed by the senior surgeon, showed a stable operating time of 10:00 min with a standard deviation 3:19min and complication rate of 2%.

Approximately 29 million cataract surgeries are performed annually worldwide, with demand expected to reach 50 million by 2050 [1]. Despite their brief duration, cataract surgeries present challenges due to their microsurgical complexity, making learning techniques difficult. The Accreditation Council for Graduate Medical Education (ACGME) mandates a minimum of 86 surgeries for ophthalmology residency completion [5].  The learning curve of surgical trainees has been extensively studied across various disciplines, with procedure time and postoperative complication rates being the common metrics [6].

Our investigation focused on the learning curve of cataract surgeries performed by two ophthalmology surgeons in an ambulant eye centre, comparing their outcomes with established literature. In the cataract surgery, the stable procedure times, indicative of refined surgical skills and confidence, typically emerge after approximately 80 surgeries, marking the plateau phase [7]. In our study, the results of Operator A were consistent with existing studies, achieving a stable operative time of 15 minutes after around 90-100 surgeries. Conversely, Operator B struggled to attain a stable operative time pattern even after more than 200 surgeries. This is possibly due to challenges in surgical education exacerbated by the COVID-19 pandemic, perfectly described by Fu et al [8]. Despite a global increase in cataract surgeries in 2020, the pandemic significantly disrupted surgical training, with cancellations of elective procedures resulting in approximately 45% reduction in case load and operative opportunities for residents. This was seen especially in the hospital setting but also affected the ambulant surgeries. In our study, Operator B's inconsistent work environment led to significant fluctuations in the learning curve of cataract surgeries, while the stable environment of Operator A before COVID-19 pandemic demonstrated normal development considering the procedure time. 

Interestingly, divergent outcomes were observed in the analysis of postoperative complications. The most common complications of cataract surgery include rupture of the posterior capsule and vitreous loss [9]. Operator experience emerges as a key risk factor, making postoperative complication rates a widely accepted method for evaluating surgical competence development. Reported complication rates following cataract surgery range from 0.5% to 16%, depending on the year of residency [10]. Zafar et al.'s retrospective study analysed postoperative complication rates of 1200 cataract surgeries performed by trainees, revealing a reduction of approximately 25% per residency year [11]. In our study, we documented the rate and total amount of postoperative complication of both surgeons within one year of training. The complication rate of the Operator A was 4,86% and Operator B – 3,80 %, both being similar to the statistics in the literature [11]. The stable pattern of the learning curve was reached after 80 surgeries by both trainees. The most common complication was the rupture of the posterior capsule (1,8% by Operator A and 2,17% by Operator B). The situation was then corrected by the supervisor.

The learning trajectory observed in Operator A in our study reflects the typical learning curve of ophthalmology trainees in cataract surgery, stabilizing after approximately 80 surgeries. Previous investigations into this learning curve have primarily taken place within hospital settings [7]. Our study, however, represents the first exploration of the learning curve of ophthalmologists in an ambulatory care centre — a novel and valuable perspective that could significantly impact the training curriculum for young ophthalmologists.

Many residents in large hospitals encounter difficulties in accumulating their surgical case load and completing their logbooks. The revelation that less complex surgeries, such as cataract surgery, can be effectively taught in ambulatory settings has the potential to ease the congestion in large hospitals and enhance accessibility to surgical skill development for all residents. Early exposure to operative skills is crucial in ophthalmology training, as it facilitates smoother learning curves throughout residency [11]. Therefore, the integration of resident education into ambulatory settings could significantly improve and enhance the quality of the overall ophthalmology curriculum.

The learning patterns observed in Operator B within our study highlight the importance of uninterrupted skill acquisition. While fluctuations in operative times occurred due to interruptions in case load, there was no significant effect on postoperative complications. This emphasizes two key points: firstly, it is insufficient to assess surgical skill acquisition solely based on postoperative complications, and secondly, the continuity of practice significantly influences proficiency in motor skill acquisition. Neurological studies further support this notion, indicating that sustained and frequent reactivations yield superior learning outcomes, similar to those achieved through extensive practice sessions, whereas sporadic reactivations result in minimal gains [12]. The lack of continuity poses a prevalent challenge in surgical education, particularly within large hospital settings, affecting the pace and adequacy of skill acquisition.

As cataract surgery emerges as one of the most sought-after surgical procedures globally, it is important to prioritize rapid yet comprehensive education for young ophthalmology trainees to meet this escalating demand [1]. Currently, cataract surgery training predominantly occurs within large hospital settings, leading to competition among trainees for cases and potentially hindering learning due to reduced case exposure.

In our study, we investigated the learning curve of cataract surgery within an ambulatory eye centre. Our findings show that once a consistent caseload is established, the learning curve of cataract surgery in ambulatory settings closely mirrors that observed in hospital settings. This suggests a promising strategy whereby the distribution of cataract surgery training to ambulatory settings could reduce the pressure on large hospitals, accelerate the learning process, and improve its quality for young ophthalmologists. Further research is warranted to explore the learning curves of other ophthalmic practices and to increase our understanding of effective training environments and methods in ophthalmic education.

We would like to thank the participants in this study and the personal of the eye centre in Bruchsal, Germany.

The authors of the study have no competing interests.

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