Ophthalmology was one of the foremost branches in medieval Islamic medicine. The oculist or kahhal (کحال), a somewhat despised professional in Galen’s time, was an honored member of the medical profession by the Abbasid period, occupying a unique place in royal households. The specialized instruments used in their operations ran into scores. Innovations such as the “injection syringe”, a hollow needle, invented by Ammar ibn Ali of Mosul, which was used for the extraction by suction of soft cataracts, were quite common.

Muslim physicians deserve much praise for their descriptions of ophthalmological pathology. They were the first to describe such conditions as pannus, glaucoma (described as ‘headache of the pupil’), phlyctenulae, and operations on the conjunctiva. They were the first to use the words 'retina' and 'cataract'. They also pioneered the field of optics. The list of Muslim contributions to Ophthalmology is anything but brief.
 

To become a practitioner, there was no one fixed method or path of training. There was even no formal specialization in the different branches of medicine, as might be expected. But some students did eventually approximate to a specialist by acquiring proficiency in the treatment of certain diseases or in the use of certain drugs. “The Prince of Physicians”, the Persian (Iranian) Avicenna, for example, was held to be more proficient than most others in his treatment of nervous diseases, and hence a large number of psychological cases were brought to him, the most famous being the Samanid prince Nooh ibn Mansur who thought of himself as a cow, and who was cured by Avicenna who was no more than 17 years of age. Avicenna himself benefited from the instruction of many teachers, ranging in subject from geometry to theology.

Nevertheless it was standard and necessary to learn and understand the works and legacy of predecessors, if one was to excel and surpass others in the field. Among those one can mention The alteration of the eye by Yuhanna ibn Masawayh, the great Nestorian Christian physician, whose work can be considered the earliest work on Ophthalmology, only to be eclipsed by that of none other but Hunain ibn Ishaq, known in the west as Johannitius, for his work The ten treatises of the eye.
Bukhtishu ibn Jurjis, chief physician to the great Caliph Harun al-Rashid; or pay for the unfortunate death of his patient or failure of his treatment with his own life, as was often the case with physicians treating many a royalty.

But in general, the fee varied according to the status of the physician and the patient. The life of Ibn Masawayh, can perhaps be quite instructive in this regard: When still unknown and still a so called “road-side” physician in Baghdad, in return for successfully treating a servant suffering from Ophthalmia, he was paid with a daily allowance of bread and meat and sweets and a promise of a monthly salary of a few silver and copper coins. When The Vizier fell ill and Ibn Masawayh achieved similar success with him, his salary rose to 600 silver dirhams a month, food for two mules, and the services of five servants. And when he finally obtained the rank of chief ophthalmologist to the Khalifah, his salary was fixed at 2000 dirhams a month plus gifts valued at 20,000 dirhams a year, including forage for his mules as well as the services of a number of servants.