Interventional cardiologists and other workers in catheterization labs who don't wear protective glasses are exposed to surprisingly high levels of ionizing radiation to their eyes, resulting in changes linked to early stage cataract development, according to two studies.
One study in Malaysia found that the posterior subcapsular opacities of the eye lens were five times higher for exposed nurses and interventionalists who did not wear leaded glasses than for medical professionals who were not exposed to ionizing radiation. This first report is published in the August edition of Catheterization and Cardiovascular Interventions.
Occupational exposures received during interventional cardiology procedures are the highest doses received by health professionals," the authors wrote. "With respect to ocular exposure, the increasingly larger
workload typical of many modern catheterization suites, a lack of training in radiation protection and unavailability or non-use of radiation protection for the face and head may result in doses to the eye sufficient to cause cataract."
The finding "indicates there's an urgent need to educate these professionals in radiation protection to reduce the likelihood of cataract," the authors say.
The second study, published this month's journal Radiation Research found interventional cardiologists and others in Montevideo, Uruguay and Bogotá, Colombia had a risk of lens changes more than three times greater than unexposed healthcare workers.
These reports are the first studies to document this phenomenon, says a leading author of both reports, Norman J. Kleiman, Director, Eye Radiation and Environmental Research Laboratory at the Mailman School of Public Health at Columbia University in New York.
Interventionalists have long known that they're exposed to these risks on a daily basis, and rules require that they be well protected from the neck down by a thyroid collar, a lead apron, and a curtain and in some cases a ceiling suspended screen, and other safeguards, Kleiman says. "But there are no federal or state regulations or international rules that mandate any kind of head, neck and face protection."
That's because it was commonly believed that the health risk threshold for radiation-caused cataracts was "about 10 to 50 times higher than what we now think the real values are. But based on those (earlier) published studies, people said 'I don't have to worry about it,' and didn't wear (eye) protection."
"We can't yet say for certainty that these individuals are going to progress to visual disability or need for cataract surgery," Kleiman says, "but based on certainly animal data and all human data we have so far, radiation cataract is progressive, not reversible and it gets worse in time."
He adds: "We're now seeing these changes in people at age 30, 40, 50, well below the age which we would expect them to get cataracts due to normal aging."
The problem has already started to become noticeable in the U.S. "We know from some of the older cardiologists who complain they don't see the fluoroscopy screen as well as they used to." And, he adds, "anecdotally, we know that sometimes what they do is turn up the gain (for better visualization), which increases the X-ray dose, so you're accelerating the problem," Kleiman says.
He likened the danger to that of "the canary in the mine," with a potential risk for higher rates of head and neck cancer or even brain tumors, because of occupational exposure to radiation in healthcare procedures.
"If they're not protecting their head, there's potential risk to anything above the neck," Kleiman warns.
Representatives of the American College of Cardiology could not be reached for comment, but Paul Teirstein, MD, a well-known interventionalist at Scripps Clinic in La Jolla, CA, says he's skeptical that the problem is that pronounced in the U.S. "Everybody I work with wears them (leaded goggles). And it's surprising to me that that would not be a routinely used by the doctors in the study. If they weren't fully protected, I would have to ask, 'Why weren't they?' "
Kleiman responded that he knows many U.S. cardiologists who tell him it just isn't a routine practice, something he hopes later research will prove.
These studies were done in other countries because International Atomic Energy Agency was interested in funding them there, but he also has a study underway to look for lens changes in interventionalists and others who work in catheterization labs at Columbia.
The studies were performed during cardiology conferences with comprehensive dilated slit-lamp exams. Each participant also was given a questionnaire asking about their workload exposures, use of protective screens and personal protective devices, and where they worked in the catheterization labs.
Lifestyle and medical factors also were explored, including sunlight exposure, steroid use and cigarette smoking, which could have a small bearing on the result as well.
Kleiman emphasized that in many lab settings where radiation is used, nurses tend to not take precautions as seriously because they are usually farther away. "But we're noticing periods of time when the nurses are getting higher doses because they're on the other side of the table where there's less protection. They presume they're less exposed so they don't protect themselves as much. But now we're seeing changes in the nurses' eyes as well."
In the first study, authors included researchers from institutions in Serbia, Austria, Malaysia and Spain as well as Kleiman. In the second report, Kleiman worked with researchers from Colombia, Austria, Uruguay, and Madrid.
Kleiman is a member of committees associated with the International Commission on Radiological Protection and the National Council on Radiation Protection and Measurement.