At a watershed? Technical developments in wireless capsule endoscopy.

This article reviews some of the technical developments that allowed the introduction of the wireless capsule 10 years ago into human usage. Technical advances and commercial competition have substantially improved the performance of clinical capsule endoscopy, especially in optical quality. Optical issues including the airless environment, depth of focus, dome reflection, the development of white light light-emitting diodes, exposure length and the advent of adaptive illumination are discussed. The competition between charge coupled devices and complementary metal oxide silicone technologies for imaging, lens improvements and the requirements for different frame rates and their associated power management strategies and battery type choices and the introduction of field enhancement methods into commercial capsule technology are considered. Capsule technology stands at a watershed. It is mainly confined to diagnostic small intestinal imaging. It might overtake other forms of conventional diagnostic endoscopy, especially colonoscopy but also gastroscopy and esophagoscopy but has to improve both technically and compete in price. It might break out of its optical diagnostic confinement and become a therapeutic modality. To make this leap there have to be several technical advances especially in biopsy, command, micromechanical internal movements, remote controlled manipulation and changes in power management, which may include external power transmission.