Ophthalmology(salakya)

Ophthalmology is the branch of medicine which deals with the diseases and surgery of the visual pathways, including the eye, brain, 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 considered 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". 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 patients when told that they may have an eye problem will be more concerned about diseases that affect vision than other, more lethal diseases[citation needed]. 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[citation needed].
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 BCE in India. 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.[1][2] 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.

Alexandrian studies
Alexandrian studies extensively contributed to knowledge of the eye. Aëtius tells us that Herophilus dedicated an entire study to the eye which no longer exists. In fact, no manuscripts from the region and time are known to have survived, leading us to rely on Celsius' account—which is seen as a confused account written by a man who did not know the subject matter. From Celsius it is known that the lens had been recognised, and they no longer saw a fluid flowing to the brain through some hollow tube, but likely a continuation of layers of tissue into the brain. Celsius failed to recognise the retina's role, and did not think it was the tissue that continued into the brain.


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.