 In order to tint her blue eyes brown for the part of Leela,  Louise Jameson (qv) wore colored contact lenses that made  everything appear red. Jameson found the effect so difficult to work  through that she petitioned the producers to change Leelas eye  color; this was duly done at the end of "Horror of Fang Rock", where  a powerful explosion causes "pigmentation dispersal" in Leelas  eyes, changing them from brown to blue.