August 2008




Improved error tool identified

by Rich Daly EyeWorld Contributing Editor 



Common errors in cataract surgery can be avoided through an examination adapted for ophthalmology

Can a tool used by the nuclear power and aerospace industry serve ophthalmology as well? The authors of a recently published study that applied human reliability analysis (HRA) as a tool to quantify errors during small incision cataract surgery think so.

The researchers sought to move beyond the traditional assessment tool for surgical competence that involves an audit of surgical complications or adverse outcomes. “This has several problems,” wrote the authors, led by Alan Cox, F.R.C.S., department of ophthalmology, Ninewells University Teaching Hospital, Dundee, United Kingdom. “It is by its nature retrospective in that the adverse outcome has already occurred.”

They noted that surgeons being audited by themselves or others may also be tempted to alter their case mix to avoid more difficult cases. To surmount these shortcomings, the researchers looked to the HRA approach used in the nuclear power and aerospace industries to avoid “catastrophic” error. This methodology determines what may go wrong, the probability and consequences of errors, and the steps necessary to reduce the incidence of such errors to as low as reasonably possible. “The prospective and prescriptive nature of this methodology makes it attractive as a measure of surgical performance and it has been successfully adapted for use with other surgical specialties,” the authors noted.

The study used HRA to assess 16 consecutive phacoemulsifications performed by one surgeon and found that although there were no complications or adverse outcomes associated with any of the operations, 84 errors, which could potentially have caused a complication, were noted. The most common error was difficulty in “cracking” the nucleus.

The study, published in the March issue of the journal Eye, was titled “Human reliability analysis: a new method to quantify errors in cataract surgery.”

Richard S. Hoffman, M.D., clinical associate professor of ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, said that because errors often occur due to many things beyond the surgeon’s control, the approach can help reduce the odds that such errors will eventually “catch up with him” and result in a complication.

“I think that any means of analysis that brings these ‘errors’ to a surgeon’s awareness so that they can be corrected are helpful,” Dr. Hoffman said.

Stuart Osborne, M.R.C.Ophth., F.R.C.SEd.(Ophth.), oculoplastic fellow, Queen Victoria Hospital, East Grinstead, United Kingdom, agreed that the detection of errors gives valuable information which could be useful in improving the skills of surgeons and reducing the risk of patients suffering complications of surgery. Many procedures only have luck keeping errors from becoming complications.

“Equally, a procedure which has gone entirely smoothly with no errors whatsoever could be complicated by patient factors [such as] a cough, breath holding, sudden movement, or by factors relating to the cataract itself, [such as] posterior polar lens opacity or weak zonules in pseudoexfoliation syndrome,” Dr. Osborne said. “As a result, using complication rates as a measure of surgical competency may be inaccurate.”

Both surgeons noted that although the size of the study was small in terms of number of cases studied, the design seemed reasonably sound, and overall the conclusions appeared justified.

Dr. Hoffman attributed the large number of errors found to the study’s use of a beginning phaco surgeon, and expected the number would be much lower with a more experienced surgeon.

Although he doubted the usefulness of regularly using the HRA approach for established surgeons, Dr. Hoffman said this type of analysis would be very helpful for any surgeon wanting to improve his surgical skills.

“I think it would be very interesting to perform the same analysis on surgeons of different experience levels,” he said. “Do surgeons who have been in practice for 10 years have significantly fewer complications?”

Both Drs. Hoffman and Osborne agreed with the authors that the analysis would be extremely helpful for residents.

The use of these techniques, Dr. Osborne said, could assist in the surgeon-in-training attaining experience more quickly by identifying errors early, which may not otherwise be appreciated unless a complication or near-miss occurred.

Both surgeons would also consider using the HRA approach to analyze their own surgical technique.

Dr. Osborne encouraged a further examination of error rates to see if they are proportional to complication rates through random sampling of two cohorts of patients, one suffering complications and one not suffering complications. The results could then be independently analyzed.

Editors’ note: Drs. Hoffman and Osborne have no related financial interests related to their comments.

Contact information
Hoffman: 541-687-2110,

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