Historical Vignette: Robert Marcus Gunn (1850–1909): Scottish Ophthalmologist, Skilled Observer, and Gifted Teacher

Robert Marcus Gunn was a Scottish ophthalmologist who studied med icine at the University of St. Andrews and the University of Edinburgh, eventually moving to Moorfields Eye Hospital, London, where he practiced ophthalmology. He was a selftaught expert in the new skill of direct ophthalmoscopy, which he readily taught to others (Figure 1). He is best known for his teachings on the Marcus Gunn phenomenon of trigemino-oculomotor synkinesis or "jawwinking"; Marcus Gunn pupil or "dynamic anisocoria"; the retinal findings of Marcus Gunn dots; and Gunn's crossing sign .