Cataract skills: how do we judge competency?

The practice of medicine is undergoing continual change. For trainees, the transition from a Halstedian apprenticeship to competence-based models of surgical training and assessment has been accelerated by European Working Time Directives, public/regulatory expectations and funding pressures.

For qualified practitioners, revalidation will demand evidence of practice to a good standard. To successfully revalidate, ophthalmologists are expected to demonstrate competence if they undertake (phacoemulsification) cataract surgery, the commonest operation in the UK¹.

We pose two key questions: what are reasonable minima for (1) the number of operations before trainees can operate independently in a safe and timely manner (acquisition of competency) and (2) for consultants to maintain competency?

Like our colleagues in other specialties, the Ophthalmic Specialty Training syllabus parallels the UK Intercollegiate Surgical Curriculum Programme, with objective checklists and global rating scales that qualitatively assess operative skills. One example is the Objective Structured Assessment of Technical skills, originally developed by general surgeons and now validated across various surgical disciplines including ophthalmology.

Our focus on operative numbers is due to the delicate 4 μm window of error that phacoemulsification surgeons must contend with. Furthermore, in other specialties (e.g. ENT, plastics, maxillofacial surgery) microsurgery is deemed a higher surgical, non-core skill, whereas ophthalmic trainees are assessed from the very first year.

To achieve Certificate of Completion of Training, plastic surgery trainees must perform at least 22 microvascular anastomoses. In comparison, the seven-year UK ophthalmology training programme specifies at least 350 full cataract operations. Three-year US residencies require 86 and in Australia ‘50 intraocular procedures’ are expected after two years of a five-year traineeship. Actual (median) cumulative totals are 500–600 for the UK² versus 100 for the USA.³

With moves towards competence-based curricula, the intensity of hands-on surgical training may have a bearing on how rapidly trainees acquire operating skills, which is more relevant in US residencies where trainees usually gain surgical experience in their senior years. Trainees improve significantly to approach the benchmark of a published ophthalmologist's (longest) average operating time of 26.8 min after the 120th case.⁴

Posterior capsular rupture (PCR) is the commonest complication of phacoemulsification. Widely used as a surgical quality benchmark; it is a likely key quality indicator for revalidation.¹ PCR rates range from >5% for junior trainees⁵ to <1.5% for independent surgeons, with less variation in complications between seniors.¹ UK trainees’ logbook reviews demonstrate significant decreases in complication rates with increasing experience.⁶ One review of 680 trainee operations over four years saw vitreous loss rate halved from 5.1% to 1.9% after the first 80 cases, correlating with significant falls in mean phacoemulsification time.⁷

While this indicates ‘80’ as a possible minimum, trainees’ efficiency continues improving well beyond this,⁷ and complications keep falling after the first 200 cases. Based on the peer-reviewed literature, and allowing for variation in trainee skills, we suggest that full completion of at least 250 cataract operations should be expected to achieve baseline competence. This target operative volume would be augmented by e-learning, surgical simulators and electronic logbooks facilitating continuous audit.

For consultants performing cataract surgery, sparse data exist on maintaining competence, with no universally agreed ‘minimum volume threshold’ of operations. In comparison, large European consensus studies have defined operative minima in vascular surgery, e.g. over 50 carotid artery stents p.a. to maintain competence.⁸ In the UK there is no general acceptance of ‘cataract specialists’ and while predictably challenging cases do gravitate to subspecialists in complex anterior segment surgery (e.g. corneal surgeons), many consultants are reluctant to refer challenging cases for fear of de-skilling.

Probably the best judge of maintaining competence for cataract surgery will be PCR rates. Unfortunately, this blunt instrument means high-volume cataract surgeons with exceptional skill who attract challenging cases may have apparently higher PCR rates than surgeons who do one uncomplicated case a year and have unblemished records. While current practice generally accepts a 2% PCR rate, our task is hampered by discrepancies in definitions of ‘high-volume’ surgery and the lack of case-mix analysis from most studies. As with other specialties,⁹ recent reports demonstrate clear volume–outcome relationships across all categories of surgical volume, with complication rates below 0.8% for consultants performing 50–250 cataract procedures (the lowest annual volume category).¹⁰

From these studies, 50 seems a sensible contender for the minimum annual cataract case volume for ophthalmologists to maintain competency, and with six weeks of annual leave and two weeks of study leave this equates to at least five cases a month. Many would question the acceptance of this relatively low number and we would suggest that the definition of maintaining competence for cataract surgery should include reporting PCR rates. In an era when the NHS medical director proposes publishing national surgeon league tables, assuming that ‘competent’ cataract surgeons should have a PCR no higher than 2%, we propose that ophthalmologists reporting PCR rates above 4% in any one year should have their case-mix and surgery reviewed, while those with PCR rates between 2% and 4% might consider referring more ‘challenging’ cases to colleagues while they self-monitor their performance over the following year. For surgeons undertaking career breaks, an annual ‘transitional minimum’ of twice this number (i.e. 100 cases) could be expected upon re-entering full-time practice. In comparison, comparative recommendations for other procedures are shown in Table 1.

Table 1.

Minimum annual surgeon volume to maintain competency⁹

Procedure	Minimum annual surgeon volume
Coronary artery bypass grafting	100
Percutaneous coronary intervention	75
Aortic valve replacement	22
Abdominal aortic aneurysm repair	8
Pancreatic resection	2
Oesophagectomy	2
Bariatric surgery	20

Unlike these highly invasive procedures, cataract surgery remains a high-volume, widespread, day-case operation, that most ophthalmologists are expected to sustain irrespective of other subspecialty interests (strabismus, oculoplastics, etc.). Our proposals are controversial, as is the suggestion of devolving cataract surgery to dedicated cataract surgeons or those with dedicated cataract sessions. We believe that the proposed PCR rates for evidencing continued competence will evolve over time and ophthalmologists should be able to decline to continue performing cataract surgery in return for more time to develop their skills in other subspecialty areas.

In view of the current drive to centralise services in the UK, particularly specialist cancer and paediatric surgery, cataract surgery reflects a model for operations which merit careful further consideration. Numerical thresholds have their nuances, and the pursuit of ‘fewer, bigger, better’ should be approached with care.

DECLARATIONS

Competing interests

None declared. The opinions expressed are the authors’ and not those of any organization.

Funding

The authors did not receive any funding or sponsorship for this paper

Ethical approval

Not required

Guarantor

CC

Contributorship

JH performed the literature survey, data analysis, manuscript drafting and revision. CC was responsible for study conception, data analysis, supervision and final approval of the manuscript

Acknowledgements

Extracts from this work were presented at the XXXVI Annual Congress of the United Kingdom & Ireland Society of Cataract and Refractive Surgeons (UKISCRS), plenary symposium debates, September 27 2012, Brighton, UK.