Ophthalmology in medieval Islam

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. Medieval Islamic scientists (unlike their classical predecessors) considered it normal to combine theory and practice, including the crafting of precise instruments, and therefore found it natural to combine the study of the eye with the practical application of that knowledge. 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 described 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'.

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.

Nevertheless, it was standard and necessary to learn and understand the works and legacy of predecessors. Among those one can mention, The alteration of the eye by Yuhanna ibn Masawayh, whose work can be considered the earliest work on Ophthalmology, followed by Hunain ibn Ishaq, known in the west as Johannitius, for his work The ten treatises of the eye. One of Hunain ibn Ishaq's innovations was to describe the crystalline lens as being located in the exact center of the eye.

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