Blue light endoscopy

The introduction of high intensity proximal light sources has greatly improved the already high standard in technique of endoscopy. They enable us to illuminate the periphery of the bronchi. The advantage of better illumination must, nevertheless, be paid for with a levelling of contrast, as the bright light outshines the fine differences ( e.g. , tubercles in the mucous membrane). In order to heighten the contrast, first theoretical, then practical tests were carried out with different colored lights. Filters (red, green, yellow and light blue) were placed in front of the light source and the subjective perceptible changes in contrast examined. These tests showed that the light blue filter gave a heightened contrast between light and dark red as well as between yellow and red. Intra‐ and submucosal nodules, scars, metaplasias, hyper‐ and parakeratoses as well as precancerous conditions are more clearly visible in the mucous membrane. Circumscribed lesions are better seen and specimens for histological verification are more accurately located for biopsy. Foreign bodies are more easily grasped. The remaining filters heighten the contrast in special cases (such as mycosis and colored foreign bodies). Individual filters or multifilter discs placed between the light source and the glass fiber light carrier are easy to manipulate, so that colored light can be employed in routine bronchoscopy in order to improve diagnosis.