Three vital ocular dyes used to examine the anterior eye are sodium fluorescein, lissamine green and rose Bengal. However, until March 2020 the legality of lissamine green for use by eye care practitioners in the UK was unclear. This paper reviews the historical and current uses of lissamine green dye, traces the changes to its legal position in the UK, examines the safety profile of the dye, considers how best to optimise its use in optical practice, and discusses the advantages of using lissamine green in addition to sodium fluorescein in anterior-eye assessment.