He also works as a consultant to the ophthalmic industry. He was the Head of Department of Applied Optics at City & Islington College from 1986 to 1995 where he had taught optics, ophthalmic lenses and dispensing from 1964. He is recognised as an international authority on the design of spectacle lenses and has written several books including Principles of Ophthalmic Lenses, first published in 1967 and now in its fifth edition, which is recognised as a standard text on the subject and has been translated into Mandarin. His most recent book, Ophthalmic Lenses & Dispensing (3rd Edition 2004), has been translated into Russian. He is the author of some 200 papers on ophthalmic lenses, contact lenses, intra-ocular lenses and dispensing and a consultant editor to the Optician magazine. He holds patents for aspheric spectacle lenses and intra-ocular lenses. He has also produced several educational CDs and runs a web-based course in Spectacle Lens Design leading to the qualification FBDO(Hons) SLD.