April 2008




Most common ophthalmic surgical error

by Vanessa Caceres EyeWorld Contributing Editor


Universal protocol could help prevent more errors

Although universal protocol may decrease surgical errors, there’s always room for human error. During ophthalmic surgery, the errors that occur most often are implantation of the wrong IOL, operating on the wrong eye, and blocking the wrong eye with anesthesia, according to a study published in the November 2007 issue of Archives of Ophthalmology and led by John W. Simon, M.D., Department of Ophthalmology, Lions Eye Institute, Albany Medical College, N.Y.

“Although they usually cause little or no permanent injury, consequences for the patient, physician, and the profession may be serious,” the study investigators wrote. “Measures to prevent such confusions deserve the acceptance, support, and active participation of ophthalmologists.”

The retrospective study reviewed 106 cases of surgical confusion in ophthalmology—42 from the Ophthalmic Mutual Insurance Company and 64 from the New York State Health Department. The cases occurred between 1982 and 2005. The study categorized each error in one of five categories: wrong implant, wrong eye block, wrong patient or procedure, wrong eye, or wrong transplant. Each error also received an injury severity score ranging from one (i.e., temporary or insignificant) to four (i.e., severe permanent injury or uncorrectable vision loss).

Although the incidence of error found in the data is relatively low—an average of 69 cases per 1 million—this number is still 10 times the quality-defect standard accepted by the manufacturing industry, the investigators wrote.

Study results

The most common error was implantation of a wrong IOL—this occurred in 63% of cases (67 patients). Seventeen of the cases were tracked to pre-op problems; 46 cases occurred intra-operatively.

“The cause in almost every [intra-operative] case was failure to check the lens specifications properly before implantation,” the investigators wrote. “Typically, the OR clerk or circulator pulled the wrong lens, and its parameters were not verified in the OR before implantation.” Some intra-operative confusion was noted because surgical staff had trouble reading the implant package.

Two patients who had the wrong IOL implanted developed corneal edema, and glaucoma occurred in another patient, who required a drainage implant and had a final visual acuity of 20/40 with visual field loss.

Investigators tracked liability payments in 26 of the wrong implant cases. Six cases involved liability payments made by the surgeons, ranging from $6,000 to $6,500; nine cases were settled by the insurance company with a mean payment of $36,667. The glaucoma case was settled for $87,500.

Injection of anesthesia in the wrong eye occurred in 13% of cases (14 patients); most of these cases lacked a site marking to indicate the correct eye for operation. In all cases, the anesthesia wore off, and surgery was eventually performed on the correct eye.

The study found the wrong patient was operated on or the wrong procedure was performed in eight cases. The causes that investigators found for these incidents included both staff confusion over patient identification as well as patient confusion. For example, one patient at a glaucoma clinic who was referred for visual field examination responded when another patient was called for trabeculoplasty; that wrong patient then had that procedure. In another instance, a patient with astigmatism cancelled his LASIK surgery at the last minute, and his parameters were mistakenly used to treat both eyes of a hyperopic patient.

Although not all instances of wrong patient or procedure errors involved liability payment, the astigmatism case was settled for $85,000, and another case was settled for $95,515.

Fourteen percent of cases (15 patients) involved operating on the wrong eye. “In most cases, appropriate site markings had not been made, and a time-out had not been performed,” the investigators wrote. Finally, the study tracked two cases where the wrong tissue was transplanted during penetrating keratoplasty. In both cases, the incorrect tissue was stored in the OR refrigerator.

Fourteen cases received a high severity score of three or four. Many of these errors led the medical institutions involved to revise their policies regarding site marking or to update other steps usually taken to prevent error.

Tracking the malpractice claims, incidents, and lawsuits from the study, the investigators concluded that these cases are “relatively likely” to result in an indemnity payment.

Use of universal protocol would have prevented confusion in 85% of cases (90 patients).


The medical profession as a whole needs a more open and pro-active attitude about medical errors such as the ones tracked in the study, Dr. Simon said.

“When a medical mistake happens, the doctors, nurses, and everyone involved feels terrible and defensive,” he said. “But defensiveness and the veil of secrecy encouraged by authorities at hospitals and state health departments interfere with doing something intelligent.” For example, states such as Florida that take a punitive approach toward physicians when medical errors occur only serve to further hide error reporting, Dr. Simon said.

“The airline and defense industries have a more enlightened attitude about errors than we do in medicine,” he said.

The universal protocol from the Joint Commission on Accreditation of Healthcare Organizations, designed to help prevent medical errors, is helpful, Dr. Simon said.

“I think doctors have become more accepting of this kind of safeguard than they used to be,” he said.

Ironically, it’s not inexperienced physicians who are making the errors, Dr. Simon said. Often, the errors occur at busy surgical centers or in situations where more people are involved in the procedure, such as in cases with the wrong IOL implanted.

“As hypothesized, such factors as switched schedules; distracted, inexperienced, or changing personnel; inadequate pre-operative verification procedures; lack of uniform site marking; and breakdown of communication between the surgeon and the patient and his or her family were identified in most cases,” the investigators wrote.

Switched schedules are a common problem that can lead to errors, said Steve H. Dewey, M.D., Colorado Springs, Colo. “Just yesterday we had four patients not in the scheduling slots we assigned them to,” he said. He could not verify how the scheduling mix-up occurred.

Another everyday dilemma is patients who are confused about the eye in which surgery will be performed, Dr. Dewey said. The patient may tell OR staff it’s the left eye that is slated for surgery, even though the surgeon has repeatedly explained it’s the right eye. To help cut down on the risk of errors, Dr. Dewey marks the site of surgery pre-op. “It’s a mandate at one of the hospitals I work for, but I liked it enough to take it to my surgical center,” he said.

He also explains the pre-op IOL selection process to OR staff who will regularly assist with ophthalmic surgery. “It gets them to understand the complexity of picking the correct IOL even before we get to the OR,” he said. “It builds a nice rapport with the OR staff.”

Editors’ note: The physicians interviewed have no financial interests related to their comments.

Contact Information

Dewey: 719-633-9869, deweys@prodigy.net

Simon: 518-533-6502, simonj@mail.amc.edu

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