Open Access Open Badges Study protocol

Occupational cataracts and lens opacities in interventional cardiology (O'CLOC study): are X-Rays involved?

Sophie Jacob1*, Morgane Michel1, Christian Spaulding2, Serge Boveda3, Olivier Bar4, Antoine P Brézin5, Maté Streho5, Carlo Maccia6, Pascale Scanff7, Dominique Laurier1 and Marie-Odile Bernier1

Author Affiliations

1 IRSN - DRPH/SRBE/Laboratoire d'Epidémiologie, Fontenay-aux-Roses, France

2 Cochin Hospital, Paris Descartes University and INSERM U 909, Paris France

3 Clinique Pasteur, Toulouse, and Groupe Rythmologie Stimulation Cardiaque/SFC, France

4 Clinique St Gatien, Tours, and Groupe Athérome Cardiologie Interventionnelle/SFC, France

5 Paris Descartes University APHP Centre Cochin Ambulatoire d'Ophtalmologie, Paris, France

6 Centre d'Assurance de qualité des Applications Technologiques dans le domaine de la Santé, Bourg-La-Reine, France

7 IRSN - DRPH/SER/Unité de Suivi et d'analyses des Expositions Professionnelles, Fontenay-aux-Roses, France

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BMC Public Health 2010, 10:537  doi:10.1186/1471-2458-10-537

Published: 8 September 2010



The eye is well known to be sensitive to clearly high doses (>2 Gy) of ionizing radiation. In recent years, however, cataracts have been observed in populations exposed to lower doses. Interventional cardiologists are repeatedly and acutely exposed to scattered ionizing radiation (X-rays) during the diagnostic and therapeutic procedures they perform. These "low" exposures may cause damage to the lens of the eye and induce early cataracts, known as radiation-induced cataracts. The O'CLOC study (Occupational Cataracts and Lens Opacities in interventional Cardiology) was designed to test the hypothesis that interventional cardiologists, compared with an unexposed reference group of non-interventional cardiologists, have an increased risk of cataracts.


The O'CLOC study is a cross-sectional study that will include a total of 300 cardiologists aged at least 40 years: one group of exposed interventional cardiologists and another of non-interventional cardiologists. The groups will be matched for age and sex. Individual information, including risk factors for cataracts (age, diabetes, myopia, etc.), will be collected during a telephone interview. A specific section of the questionnaire for the exposed group focuses on occupational history, including a description of the procedures (type, frequency, radiation protection tool) used. These data will be used to classify subjects into "exposure level" groups according to cumulative dose estimates. Eye examinations for all participants will be performed to detect cataracts, even in the early stages (lens opacities, according to LOCS III, the international standard classification). The analysis will provide an estimation of the cataract risk in interventional cardiology compared with the unexposed reference group, while taking other risk factors into account. An analysis comparing the risks according to level of exposure is also planned.


This epidemiological study will provide further evidence about the potential risk of radiation-induced cataracts at low doses and contribute to cardiologists' awareness of the importance of radiation protection.

Trial Registration