Juvenile myelomonocytic leukaemia (JMML), previously called juvenile chronic myelogenous/myeloid leukaemia, is a disorder of infancy and early childhood associated with clonal overproduction of immature myeloid cells, leading to organ infiltration, infection, and failure. Hallmarks include leucocytosis, often with monocytosis, hepatosplenomegaly, increased HbF levels, and no Ph chromosome.^1,2 Allogeneic bone marrow transplant is considered the only curative therapy.³ Ocular involvement has only been reported on one occasion.⁴

Case report

A 3 year old boy with a 2 year history of JMML, with remission and subsequent relapse after allogeneic haematopoietic cell transplant, was incidentally found to have a fixed, dilated left pupil at 6 mm, unreactive to light, and no perception of light. Family members …