Evaluation of an optical system in the fibercolonoscope: trial manufacture of an instrument with 30 degrees deviation optical system.

To evaluate the best optical system for colonoscopy a colonofibrescope was manufactured in which the optical system had a 30 degrees prograde deviation. In this test model, frontal view was easily obtained and close-up observations were possible. At areas with prominent semilunar folds, the zone behind them also came into full view. The bowel lumen could be visualized by angulation, the same as with conventional instruments. The passage trough the sigmoid-descending junction was easy, and visualization or the colon up to the distal transverse colon was accomplished within a short time in the majority of cases without fluoroscopic control.