Inert gas bubbling through porous plugs is commonly used to stir molten steel in ladle to ensure homogeneity and promote chemical reactions between slag and metal phases. The bubbling of gas can result in the molten metal being exposed to the air through the formation of an "eye" in the slag layer, resulting in contamination and lower steel quality. Ladle eyes have been the subject of several studies and scientific debate in recent years, focusing in the development of models to predict the size of the eye as a function of flow rate, geometrical dimensions of the ladle and slag/metal depth and the new sensors to allow control of the phenomena. This paper will critically examine the work to date and present new results based on cold modelling and industrial trials, using image and acoustic analysis to predict the stirring conditions inside the ladle.