This led him to propose the use of artificial lenses to treat cataract. He had a lens manufactured using the same material – brand name Perspex, made by ICI – and on 29 November 1949 at St Thomas' Hospital, Ridley achieved the first implant of an intraocular lens, although it was not until 8 February 1950 that he left an artificial lens permanently in place in an eye. The first lens was manufactured by the Rayner company of Brighton & Hove, East Sussex, a company which continues to manufacture and market small-incision intraocular lenses today.