Mucosal exposure to light during routine endoscopy

Background: The spectral irradiance delivered by a variety of gastrointestinal endoscopes was measured as a function of wavelength and used to estimate the amount of light delivered to the mucosal surface during routine endoscopic procedures. Methods: Spectral irradiances from seven different endoscopes were measured using a commercial spectroradiometer calibrated against a National Institute of Standards and Technology traceable source. Results: The largest maximum irradiance was 8.0 W/cm(2) obtained from an endoscope used in transillumination mode. In the typical viewing mode, the largest maximum irradiance measured was 1.6 W/cm(2). The majority of the light energy delivered by these gastrointestinal endoscopes was in the visible wavelength region (400 to 700 nm), Discussion: The measurements revealed surprisingly high light exposures in the visible wavelength range. In fact, the estimated tissue exposures can exceed by 40-fold the standards established for skin exposure to light set forth by the American National Standards Institute. Because gastrointestinal endoscopy is widely viewed to be safe, it is probable that the gastrointestinal tract has significant tolerance to light exposure.