Interventional cardiologists and nurses have a greater dose-dependent risk of posterior lens opacities when radiation protection tools are not used. Employing ocular radio-protection may help mitigate this risk, according to a sub study of the RELID trial published online June 14 in Catheterization and Cardiovascular Interventions.
“Interventional cardiologists are among the most frequent and intensive users of fluoroscopy in the medical profession,” the authors wrote. “Over the past 30 years, the advent of interventional cardiac procedures has resulted in a dramatic increase in occupational x-ray exposure to interventional cardiologists and nurses, which has led to an elevated risk of radiation injury.”
To investigate radiation-associated lens changes among interventional staff, Olivera Ciraj-Bjelac, of the Vinca Institute of Nuclear Sciences in Belgrade, Serbia, and colleagues performed a dilated slit-lamp exam of the lens of 67 physicians and nurses who work in an interventional lab setting.
Additionally, the researchers performed an assessment of medical and occupational radiation exposure history, x-ray dose to the lens and other risk factors of cataractogenesis via a 26-question survey administered to the participants.
The study took place during the National Heart Association of Malaysia meeting in April 2009 and enrolled 22 age and sex matched healthcare professionals who did not work in interventional medicine as the control group.
Ophthalmologists and ophthalmic researchers examined study participants' eyes after dilation with 2.5 percent phenylephrine and 1 percent cyclopentolate. The Merriam-Focht scoring system was used to evaluate posterior lens opacities.
Two independent observers evaluated each patient and these observers were blinded to the participants' survey answers and prior history—Merriam-Focht scores of 2.0 or greater correlate with changed vision.
Ciraj-Bjelac et al estimated participants’ occupational radiation dose by assessing workload—the number of procedures carried out per week and typical values of relevant exposure parameters as fluoroscopy time, number of cine series per procedure and number of frames per series.
The researchers found the prevalence of radiation associated posterior lens opacities to be 52 percent and 45 percent for interventional cardiologists and nurses, respectively. These rates were 9 percent for the control group.The relative risk of lens opacity was 5.7 and 5.0 for interventionists and nurses, respectively.
Results showed that ocular doses ranged from .01 Gray (Gy) to 43 Gy—mean values were 3.4 Gy and 1 Gy. According to the researchers, those with limited work experience—several months to a year in the cath lab—accounted for the low numbers of exposure.
One individual with a cumulative dose of 43 Gy reported working for 18 years without use of any protective devices and accounted for the only such high value,” the authors wrote.
The mean value of ocular dose was 1.1 Gy for interventional cardiologists and 0.64 Gy for nurses, the researchers reported.
Thirty-four subjects had posterior subcapsular cataract (PSC) changes of 0.5 or higher in either eyes (51 percent), and posterior lens changes were observed in two subjects (9 percent).
Twenty-nine interventionalists and five support staff had lens changes and 33 percent were exposed to more than 1 Gy.
“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 eyes sufficient to cause cataract,” the authors wrote.
The authors said that while results showed a relationship between workload and x-ray exposure to the lens of interventional staff, further studies are needed to document these lens changes before making definitive claims about the risk of visual disabilities.
“The absence of formal training in radiation protection for cardiologists in many countries and, in fact in large parts of the world, a lack of awareness and proper knowledge of the harmful effects and the unavailability of appropriate shielding devices can contribute to an increased risk of eye injuries in interventional cardiology,” the authors wrote.
“Furthermore, knowledge of individual dose levels helps to increase awareness about radiation. Thus, good training, skilled operators and use of radiation protection devices are essential