Eye exams require strict adherence to protocols
Reason for exam should be clear to physician
(Editor’s note: The following two articles are the second part of our coverage concerning the Secaucus, NJ, train wreck that was caused by an engineer who hid his diabetes and failing eyesight from his employer. For the first part of the story, including a detailed report on the role an occupational health physician’s vision exams may have played in the accident, see Occupational Health Management, June 1997, pp. 61-64.)
Occupational health physicians should not feel intimidated by the vision testing required in some work situations, but they must take the examinations very seriously, suggests an ophthalmologist who has closely studied a train wreck that was blamed, in part, on an occupational health specialist’s improper vision exam.
The National Transportation Safety Board (NTSB) in Washington, DC, recently issued a report concerning the wreck of a New Jersey Transit (NJT) commuter train operated by 59-year-old train engineer John J. DeCurtis. He was killed at 8:40 a.m. on Feb. 9, 1996, when his train ran a red stop signal and collided with another NJT train. The engineer on the other train also died. One of the 400 passengers on the trains died, and 158 were injured.
An investigation by the NTSB found DeCurtis had been a noninsulin-dependent (type II) diabetic for 19 years and, as a result, suffered from peripheral vascular disease. He was colorblind, and his right eye vision was 20/400 with correction. The vision in his left eye varied from 20/30 to 20/70 with correction. He misinterpreted a red stop signal and accelerated just before the crash.
The crash is a tragic reminder that vision examinations are much more than just a perfunctory part of an overall physical, says Anne Sumers, MD, FAAO, an ophthalmologist in Ridgewood, NJ. Sumers is also a spokeswoman for the American Academy of Ophthalmology in San Francisco, CA. (For tips on conducting vision exams, see related story, p. 82.) She has followed the Secaucus train wreck since it happened and says it is a vivid example of what can happen when occupational health physicians don’t screen properly for vision problems.
No one puts all the blame on the physician, but the evidence suggests that a better handling of the vision testing might have prevented the accident. The train engineer was able to keep his diabetes secret from his employer and the occupational health physicians who provided the annual examinations he needed to continue working.
Part of the annual examinations for NJT engineers includes testing eyesight with the Dvorine psuedoisochromatic plates, known as the PIP test, a series of 14 circular plates of polka dots with numbers in slightly contrasting colors. When DeCurtis was tested in February 1994, he missed two of the 14. When he was last tested in February 1995, he missed six of the plates. That is considered a sign of rapid vision loss, but the occupational health physician allowed DeCurtis to take another type of vision test, the Dvorine nomenclature test.
Because DeCurtis passed the second test, the doctor allowed him to continue working. The engineer was due for another physical examination the same month as the accident, so it is likely his vision had deteriorated even further by that time.
The problem is that the second vision test is not intended to detect color blindness. The first test, the one the engineer failed, is specifically designed to detect problems with color discrepancy.
Some critics have questioned whether occupational medicine physicians should perform vision exams at all, given the importance of a proper exam. A prominent occupational medicine specialist tells Occupational Health Management that the train wreck has made him reconsider the way he provides vision testing. William B. Patterson, MD, MPH, president of New England Occupational Health Center in Wilmington, MA, notes he is unfamiliar with the Dvorine exams given to the train engineer and feels that he, and most other occupational medicine specialists, could use a few pointers from an ophthalmologist.
More info is needed on vision exams
"I would welcome additional information, and I’m sure most other occupational medicine physicians would welcome some advice after reading about the fatal train wreck," Patterson says. "No one wants to be involved in something like that. If we can understand the process better, we should be able to avoid that."
While admitting the train wreck makes him more cautious about vision tests, Patterson says it would be going too far to suggest that all vision exams be referred to an ophthalmologist. The New Jersey ophthalmologist agrees.
"Occupational health physicians need good guidelines that indicate to them when an employee may need a more thorough check by someone like me, but there is no reason they can’t do the exams for most people," says Sumers. "Any competent doctor or nurse could give these exams."
The real lesson from the train wreck is that testing protocols serve an important purpose, she says. It is easy to get too jaded about routine testing, especially when the individual seems generally healthy and ready to work, she notes. That tendency may be even stronger when the testing is not firmly within the physician’s primary field of expertise.
"There is a reason these testing protocols are set up the way they are," Sumers says. "If a person fails a vision test, don’t find another test that will allow you to pass them. Remember why you’re doing the test. You are not just trying to find ways to pass the person."
Sumers compares the situation to a doctor who finds that a patient has a dangerously high blood pressure reading and then decides to test the blood pressure with a different sphygmomanometer. If the second reading is normal, perhaps the doctor would try a third sphygmomanometer or otherwise try to determine the patient’s actual blood pressure. But it would be grossly irresponsible, and unimaginable for most physicians, to just ignore the first indication of high blood pressure.
In fact, the situation with the Secaucus train wreck was even worse, Sumers notes, because the second test used was not a proper testing instrument.
"The doctor got the answer he needed from the first test. The real issue is what he did with the answer," she says. "The system could have worked."
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