Ophthalmology is a branch of medicine which deals with the diseases and surgery of the visual pathways, including the eye, hairs, and areas surrounding the eye, such as the lacrimal system and eyelids. The term ophthalmologist is an eye specialist for medical and surgical problems. Since ophthalmologists perform operations on eyes, they are considered to be both a surgical and medical specialty.
The word ophthalmology comes from the Greek roots ophthalmos meaning eye and logos meaning word , thought or discourse ; ophthalmology literally means "the science of eyes". "Opthomology" is a common mis-hearing or mis-remembering of the term. As a discipline, it applies to animal eyes also, since the differences from human practice are surprisingly minor and are related mainly to differences in anatomy or prevalence, not differences in disease processes. However, veterinary medicine is regulated separately in many countries and states/provinces resulting in few ophthalmologists treating both humans and animals.
History
The eye, including its structure and mechanism, has fascinated scientists and the public in general since ancient times. The majority of all input to the brain comes from vision. Many of the expressions in the English language that mean to understand are equivalent vision terms. "I see", to mean I understand.
Many people when told that they may have an eye problem will be more concerned about diseases that affect vision than other, more lethal diseases. Being deprived of sight can have a devastating effect on the psyche, as well as economic and social effects, as many blind individuals require significant assistance with activities of daily living and are often unable to continue gainful employment previously held while seeing.
The maintenance of ocular health and correction of eye problems that decrease vision contribute greatly to the ability to appreciate the longer lifespan that all of medicine continues to allow. Given the importance of vision to quality of life, many ophthalmologists consider their job to be rewarding, as they are often able to restore or improve a patient's sight. As detailed below, advances in diagnosis and treatment of disease, and improved surgical techniques have extended our abilities to restore vision like never before.
Sushruta
Sushruta wrote Sushruta Samhita in about fifth Century . He described about 72 ocular diseases as well as several ophthalmological surgical instruments and techniques. Sushruta has been described as the first Indian cataract surgeon. Arab scientists are some of the earliest to have written about and drawn the anatomy of the eye—the earliest known diagram being in Hunain ibn Is-hâq's Book of the Ten Treatises on the Eye . Earlier manuscripts exist which refer to diagrams which are not known to have survived. Current knowledge of the Græco-Roman understanding of the eye is limited, as many manuscripts lacked diagrams. In fact, there are very few Græco-Roman diagrams of the eye still in existence. Thus, it is not clear to which structures the texts refer, and what purpose they were thought to have.
Pre-Hippocrates
The pre-Hippocratics largely based their anatomical conceptions of the eye on speculation, rather than empiricism. They recognized the sclera and transparent cornea running flushly as the outer coating of the eye, with an inner layer with pupil, and a fluid at the centre. It was believed, by Alcamaeon and others, that this fluid was the medium of vision and flowed from the eye to the brain via a tube. Aristotle advanced such ideas with empiricism. He dissected the eyes of animals, and discovering three layers (not two), found that the fluid was of a constant consistency with the lens forming (or congealing) after death, and the surrounding layers were seen to be juxtaposed. He, and his contemporaries, further put forth the existence of three tubes leading from the eye, not one. One tube from each eye met within the skull.
Rufus
Rufus recognised a more modern eye, with conjunctiva, extending as a fourth epithelial layer over the eye. Rufus was the first to recognise a two chambered eye; with one chamber from cornea to lens (filled with water), the other from lens to retina (filled with an egg-white-like substance). Galen remedied some mistakes including the curvature of the cornea and lens, the nature of the optic nerve, and the existence of a posterior chamber. Though this model was roughly a correct but simplistic modern model of the eye, it contained errors. Yet it was not advanced upon again until after Vesalius. A ciliary body was then discovered and the sclera, retina, choroid and cornea were seen to meet at the same point. The two chambers were seen to hold the same fluid as well as the lens being attached to the choroid. Galen continued the notion of a central canal, though he dissected the optic nerve, and saw it was solid, He mistakenly counted seven optical muscles, one too many. He also knew of the tear ducts.
After Galen
After Galen a period of speculation is again noted by Arab scientists; the lens modified Galen's model to place the lens in the middle of the eye, a notion which lasted until Vesalius reversed the era of speculation. However, Vesalius was not an ophthalmologist and taught that the eye was a more primitive notion than the notion of both Galen and the Arabian scientists — the cornea was not seen as being of greater curvature and the posterior side of the lens wasn't seen to be larger.
Understanding of the eye had been so slow to develop because for a long time the lens was perceived to be the seat of vision, not as part of the pathway for vision. This mistake was corrected when Fabricius and his successors correctly placed the lens and developed the modern notion of the structure of the eye. They removed the idea of Galen's seventh muscle (the retractor bulbi ) and reinstated the correct curvatures of the lens and cornea, as well as stating the ciliary body as a connective structure between the lens and the choroid.
Middle Eastern ophthalmology
Main article: Ophthalmology in medieval IslamOf all the branches of Islamic medicine, ophthalmology was considered one of the foremost. Scores of specialized instruments were developed. Innovations such as the “injection syringe”, invented by the Iraqi physician Ammar ibn Ali of Mosul, which was used for the extraction by suction of soft cataracts, were quite common. In cataract surgery, Ammar ibn Ali attempted the earliest extraction of cataracts using suction. He introduced a hollow metallic syringe hypodermic needle through the sclera and successfully extracted the cataracts through suction.
Ibn al-Haytham (Alhazen), the "father of optics", studied the anatomy of the eye extensively. He made important contributions to ophthalmology and eye surgery and posited the first correct explanations of the process of sight and visual perception in his Book of Optics (1021). He was also the first to hint at the retina being involved in the process of image formation.
Ibn al-Nafis, in The Polished Book on Experimental Ophthalmology , discovered that the muscle behind the eyeball does not support the ophthalmic nerve, that they do not get in contact with it, and that the optic nerves transect but do not get in touch with each other. He also discovered many new treatments for glaucoma and the weakness of vision in one eye when the other eye is affected by disease. Salah–ud-din bin Youssef al-Kalal bi Hama (i.e. the eye doctor of Hama) was a Syrian oculist who flourished in Hama in 1296. He wrote for his son a very elaborate treatise of ophthalmology entitled Nur al-Uyun wa Jami al-Funun (light of the eyes and collection of rules).
Seventeenth and eighteenth century
The seventeenth and eighteenth century saw the use of hand lenses (by Malpighi), microscopes (van Leeuwenhoek), preparations for fixing the eye for study (Ruysch) and later the freezing of the eye (Petit). This allowed for detailed study of the eye and an advanced model. Some mistakes persisted such as: why the pupil changed size (seen to be vessels of the iris filling with blood), the existence of the posterior chamber, and of course the nature of the retina. In 1722 Leeuwenhoek noted the existence of rods and cones though they were not properly discovered until Gottfried Reinhold Treviranus in 1834 by use of a microscope.
Ophthalmic surgery in Great Britain
The first ophthalmic surgeon in Great Britain was John Freke, appointed to the position by the Governors of St Bartholomew's Hospital in 1727, but the establishment of the first dedicated ophthalmic hospital in 1805; now called Moorfields Eye Hospital in London, England was a transforming event in modern ophthalmology. Clinical developments at Moorfields and the founding of the Institute of Ophthalmology by Sir Stewart Duke Elder established the site as the largest eye hospital in the world and a nexus for ophthalmic research.
Professional requirements
Ophthalmologists are medical doctors (M.D.) or Doctors of Osteopathic Medicine (D.O.). who have comp
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