抄録
The colonofiberscope in the present use has a nearly orthoptic optical system (10° optical axis deviation). Although the fiberscope with right grade deviation of the optical axis (90°) was first attempted as is the gastrofiberscope, it was unsuccessful because of its narrow visaual field and of the difficulty in its insertion to the proximal portion of the colon. Secondly, the fiberscope with orthoptic visual field was tried with an insufficient result for its narrow visual field and for its short distance from the mucosa. Following them, a new fiberscope was evaluated with changeable viewing directions, that is, orthoptic and rectangular angle deviations either by changing the top lens or by rotating the prism of the instrument. Finally the fiberscope with 10° optical axis deviation was adopted. Although 20°-30° axis deviation system was most desirable, degree of deviation was limited to 10° because of its technical difficulty. This 100 deviation system, however, has some problems : Namely, observation is sometimes difficult at the strongly bending portion of the intestine or behind the prominent haustrae, and a frontal view of the lesion with a wide scope can hardly be obtained. Lately, by co-operation with optical engineers, the authors have made a fiberscope with 30° deviation optical system because the technical problems had been dissolved. It becomes possible to get a frontal view of the wide area by this new fiberscope, and there is no blind portion for observation even behind hastrae. This instrument can take a clear close-up picture, so it is thought to be useful for a close-up and magnifying observation. It is also easy to observe a same lesion from several directions. Moreover the authors can observe the intestine cylindrically as through a usual fiberscope by changing the working angle of the tip of the instrument. Therefore it has a great clinical significf ance to have increased an angle of optical axis deviation of the fiberscope from 10° to 30°.This fiberscope can be advanced very easily from the sigmoid to discending colon. In most cases, observation of the left-side colon as far as distal transverse colon is possible in a short time without fluoroscopic control. Tle anchors can see the lighting of the tip of the scope through the abdominal wall even in the descending colon and can easily confirm the position of the tip. Easy insertion of the scope to proximal colon is thought to be based on its optical system and its special shape of the tip of the instrument. So this suggests that the improvement is needed of the shape of the tip of the currently used colonofiberscope.
