sentences:  The photographic plate in the Dodge technique was soon replaced with a film camera, but was still plagued by problems of accuracy, due to the difficulty of keeping all parts of the equipment perfectly aligned throughout a trial and accurately compensating for the distortion caused by the diffractive qualities of photographic lenses.In addition, it was usually necessary to restrain a participant's head by using an uncomfortable bite-bar or head-clamp.In 1922, Schott pioneered a further advance called electro-oculography (EOG), a method of recording the electrical potential between the cornea and the retina.