He wrote the landmark textbook on ophthalmology in medieval Islam, Notebook of the Oculists, for which he was known in medieval Europe as Jesu Occulist, with "Jesu" being a Latin translation of "Isa", the Arabic name for Jesus.

In Islamic astronomy and Islamic geography, together with Chalid Ben Abdulmelik in 827, he measured the Earth's circumference, getting a result of 40,248 km (or, according to other sources, 41,436 km).

See also

• List of Arab scientists and scholars