Anatomy of the Eye

A Closer Look at the Eye

The History of Ophthalmology

An Egyptian papyrus (circa 1600 B.C.) discloses that ophthalmology, in comparison with other medical specialties of the time, was relatively advanced. Many ocular conditions—blepharitis, chalazion, iritis, cataract, trachoma, ophthalmoplegia—were already recognized entities. On the other hand, available treatments were far less sophisticated, and included the use of crocodile dung and lizard blood.

Ophthalmometer, ca 1880

In the second century A.D., Galen wrote several ophthalmic texts that described the eye as the most divine organ. He theorized that rays proceed from the brain through the optic nerve, retina, lens, and cornea, continuing in straight lines toward the object of regard. These rays would then return in exactly the same path to the lens, where vision was mysteriously manufactured and retransmitted to the brain.
Although the surgeon Susruta performed cataract surgery in India over 2,000 years ago, it was not until the mid-19th century in western Europe that a solid scientific base for the specialty was first established. Significant scientific and medical advances of the period included the development of the ophthalmoscope, an increased understanding of refractive errors and their correction, and a more sophisticated knowledge of visual physiology. The current practice of ophthalmology remains based on a firm foundation of scientific research.

As a consequence of its long history, ophthalmology has witnessed many firsts. In 1864, the American Ophthalmological Society was established as the first medical specialty organization in the United States, and in 1917, ophthalmology became the first branch of medicine to develop specialty board examinations.

A number of medical breakthroughs have been made as a result of research in ophthalmology. For example, the first successful use of antiviral agents was for the treatment of eye disease. In the area of surgery, corneal transplants were the first successful homotransplants.

Other surgical innovations include the development of laser photocoagulation, microsurgery, and the development of techniques for micromanipulation and laser photocoagulation from within the vitreous cavity itself. Modern diagnostic advances range from the use of ultrasound and fluorescein angiography to sophisticated electrophysiology and visual function studies.

These new advances continue to add challenge and excitement to the field, giving every indication that the future of ophthalmology will be as dynamic as its history.

The anatomy of the human eye.

The anterior chamber is the area bounded in front by the cornea and in back by the lens, and filled with aqueous.
The aqueous is a clear, watery solution in the anterior and posterior chambers.
The artery is the vessel supplying blood to the eye.
The canal of Schlemm is the passageway for the aqueous fluid to leave the eye.
The choroid, which carries blood vessels, is the inner coat between the sclera and the retina.
The ciliary body is an unseen part of the iris, and these together with the ora serrata form the uveal tract.
The conjunctiva is a clear membrane covering the white of the eye (sclera).
The cornea is a clear, transparent portion of the outer coat of the eyeball through which light passes to the lens.
The iris gives our eyes color and it functions like the aperture on a camera, enlarging in dim light and contracting in bright light. The aperture itself is known as the pupil.
The lens helps to focus light on the retina.
The macula is a small area in the retina that provides our most central, acute vision.
The optic nerve conducts visual impulses to the brain from the retina.
The ora serrata and the ciliary body form the uveal tract, an unseen part of the iris.
The posterior chamber is the area behind the iris, but in front of the lens, that is filled with aqueous.
The pupil is the opening, or aperture, of the iris.
The rectus medialis is one of the six muscles of the eye.
The retina is the innermost coat of the back of the eye, formed of light-sensitive nerve endings that carry the visual impulse to the optic nerve. The retina may be compared to the film of a camera.
The sclera is the white of the eye.
The vein is the vessel that carries blood away from the eye.
The vitreous is a transparent, colorless mass of soft, gelatinous material filling the eyeball behind the lens.