In clinical routine EOG we are dealing with a base line or lightinsensitive potential and a lightsensitive potential, the latter consisting of at least two different oscillations, a fast negative and a slow positive one. Any judgement of EOG without referring to the absolute level of the baseline is an incomplete one. It is no longer justified to refer to the Arden ratio as a unique parameter for EOG normalty or abnormalty. Our knowledge about the generating mechanisms of the different EOG components is insufficient. Clinical EOG examination is one way to better understanding. Statistical evaluation is not easy because of the considerable inter- and intraindividual variations. The study of uniocular diseases or affections may solve some of our problems.