Lens of the eye: Radiation dose in balloon dacryocystoplasty

PURPOSE: To evaluate the absorbed radiation dose to the lens of the eye, wh ich is the critical organ in the primary beam during fluoroscopically guide d transluminal balloon dilation of the lacrimal drainage system (balloon da cryocystoplasty) for obstructive epiphora and to evaluate the possibility o f deterministic radiation effect on the lens. MATERIALS AND METHODS: The radiation dose to the lens of the eye during bal loon dacryocystoplasty (which includes pre- and postintervention dacryocyst ography) was measured in 10 consecutive patients by using thermoluminescent dosimeters on the lids of both eyes as close as possible to the lenses. A C-arm angiographic unit coupled with a digital imaging system was used, wit h similar exposure and geometric parameters in all cases. RESULTS: The mean radiation dose to the lens of the treated eye was 4.6 mGy +/- 2.2 (dose range, 1.9-9.1 mGy) and to that of the untreated eye was 38. 5 mGy +/- 17.5 (dose range, 14.7-67.8 mGy). CONCLUSION: The lens of the untreated eye receives a higher dose than that of the treated eye because of its closer proximity to the x-ray tube in a l ateral projection. In the lens, even the highest measured radiation dose (6 7.8 mGy) still was well below the deterministic threshold for lens opacity and cataract formation.