 The two participating centres are already endowed with identical endoscopic equipment. All examinations will be performed using the same high resolution endoscope EC-590 ZW, Fujinon Inc., Daitama, Japan. The zoom function on the device will only be used during the FICE procedures. The system is equipped with the EPX 4400 processor Fujinon Inc., Japan that enables the CVC technology. This digital processing system can switch between conventional imaging and CVC imaging at any time during the procedure by means of a simple pushbutton on the endoscope. The system has up to ten 10 settings designed to select the most suitable wavelengths. In this study the CVC procedure will be performed using setting number three 3. 