Mark Treisman, the son of Wolfe Treisman, an outfitter, and of Esther (née Davis) was born in London on 10 May 1898. His paternal grandparents and several generations of his family were farmers in Lithuania until Jews were forbidden to own land there. He later changed his name to Tree and states that a cousin Herman Treissman, FRCS, was an ophthalmologist who died in 1963, although this is not recorded in *Lives of the Fellows*, Vol 4, p.412. He was educated at the Central Foundation School, Whitechapel, before entering London Hospital Medical College where he won the Sutton Pathology Prize in 1920. He recorded his indebtedness to Frank Juler, AM Levy and RJ McNeill Love. He was house physician at the Brompton Hospital and then clinical assistant to Moorfields and the Central London Ophthalmic Hospital where he won the Archer Prize in 1934. He also served as house surgeon to the Oxford Eye Hospital and as senior surgical registrar at the Birmingham and Midland Eye Hospital before becoming consultant ophthalmologist to the Birmingham Regional Hospital Board. He was also ophthalmologist to the Birmingham schools for the partially sighted, and to the Birmingham Education Committee. In 1939 he married Ann Cowen whose family included many doctors, but there is no record of them having any children. He published important papers on eye defects in partially sighted children, and on familial hyaline dystrophy. Outside his professional work he was interested in art, antiques and gardening. There is no record of his date and place of death but he was listed as deceased in the General Medical Council's list of 2 January 1985.