Benevenutus Grassus Hierosolimitanus (also called Benevenutus Grapheus/Crassus or Benvenuto Grassi of Jerusalem) (c. 1200-c. 1290[1]) was a medieval eye doctor who lived in the second half of the thirteenth century and is known for his treatise on the treatment of eye disorders Ars Probatissima Oculorum or De probatissima arte oculorum, the only published record of his work.
Based on his work, it is believed that he lived most of his life in Italy but had travelled to northern Africa.
The earliest known English work that incorporates his teachings is Philip Barrough's The Method of Phisicke (1583).
[4] The text claims that Grassus learnt from a variety of sources and practiced by travelling to various places both in the temperate and tropic areas.
He quotes Hippocrates, Galen, Johannicius and Hunayn bin Ishaq of Baghdad.