Johann Friedrich Horner (27 March 1831 – 20 December 1886) was an ophthalmologist based at the University of Zurich, Switzerland.
After receiving his medical degree from the University of Zurich in 1854, he continued his studies in Vienna, where he learned ophthalmoscopy from Eduard Jäger von Jaxtthal (1818–1884), and in Berlin, where he served as an assistant to ophthalmologist Albrecht von Graefe (1828–1870).
He returned to Zurich in 1856, and later opened his own eye clinic named "Hottinghof".
Horner's syndrome, a disorder of the sympathetic nervous system, was named after him following his description of the condition in 1869.
[1] With Alexios Trantas (1867–1960), the "Horner-Trantas spots" are named, being defined as small whitish-yellow chalky concretions of the conjunctiva around the corneal limbus[2] He was the author of numerous articles on ophthalmic medicine, published in Carl Wilhelm von Zehender's Klinische Monatsblatt für Augenheilkunde.