Nineteenth-Century Developments Related to Sight and the Eye

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Nineteenth-Century Developments Related to Sight and the Eye

Overview

While the human eye has always inspired poets and writers, this small organ was studied by ancient scholars and physicians long before the advent of modern science. Many of the words related to the study of the eye derive from the Greek (ophthalmos) and Latin (opticus) words for eye. Thus, the study of the eye is called ophthalmology, and the measure of the eye, optometry. An ophthalmologist is a doctor of medicine who diagnoses and treats diseases of the eye. An optometrist has been specially trained to give eye health and vision examinations.

While much of the structure of the eye was known at the beginning of the nineteenth century, the science developed so rapidly that its history is essentially a succession of biographies of scientists who added pieces to the puzzle. Several lesser-known physicians also developed advances in diagnoses and equipment. By the end of the nineteenth century, the knowledge of eye structure and function set the stage for the unprecedented treatments, such as laser surgery, and other advances during the twentieth century.

Background

Ophthalmology is an old science. Ancient Egyptians recognized and treated eye disorders, and surgeons in Greece operated on the eye. Aulus Celsus, a first-century a.d. Roman, summarized knowledge about the eye in his De medicina. According to legend, the Chinese invented glasses perhaps as early as 500 b.c. When Marco Polo (1254-1324) visited China in 1275, he saw many Chinese with glasses. During the golden age of Arabic medicine around 1000 a.d., famed physicians studied the eye and systematically treated eye diseases. A Jewish physician Isaac ben Soloman Israeli (832?-932?) was a noted oculist who maintained a practice outside Cairo. He wrote eight medical works in Arabic, including a treatise on ophthalmology. Paramedic oculists in the Middle Ages traveled around to different communities treating the eye and peddling crude glasses. Many of these were fitted so badly that they did more harm than good. Although many of these itinerants used magic and quackery, they are sometimes credited with founding the practice of eye care. A sixteenth-century German oculist, Geor Barisch, also wrote on eye diseases.

However, little basic knowledge was added about the eye until the eighteenth century, when knowledge emerged to set the stage for nineteenth-century advances. With new procedures for grinding lenses, glasses became more accurate. Benjamin Franklin (1706-1790) is credited with developing bifocals. In 1738 a procedure was developed for the correction of strabismus, or crossed eyes. Night blindness was discussed in 1767. In 1750 glaucoma was fully described, and in 1794 colorblindness was recognized.

Impact

At the beginning of the nineteenth century, interest in the eye and its diseases was increasing. The first course in ophthalmology was offered in 1803 at the University of Göttingen. The London Eye Infirmary was begun in 1805 and operated as a teaching hospital, establishing the first modern medical specialization. Sir William Lawrence (1783-1867) was a British eye surgeon who practiced at this infirmary. A pioneering surgeon and investigator, Lawrence wrote Treatise on the Venereal Diseases of the Eye in 1830 and Treatise on the Eye in 1833. These works were outstanding for their time.

One of the first to affect nineteenth-century investigation of visual phenomena was a Czech physiologist Jan Evangelista Purkinje 1787-1869). Receiving his medical degree in 1818, he was very interested in subjective visual happenings. He based his theories of natural science on observation and experiments. Lacking the facilities in Prague for investigation, he began self-observation of errors in perception and sensations that seemed to have no physical cause. He determined that these occurrences are not by chance, but are related to the structure and function of the eye and its nerve connections to the brain. Purkinje became interested in shadows of one's own retinal vessels as night approaches. In 1855 a contemporary, Heinrich Mueller, confirmed that rods and cones were related to the phenomena Purkinje described. Purkinje also linked visual errors or illusions to connections in the brain. Studying the importance of reflex images in ophthalmology, he recognized that the interior of the eye could be examined by a light reflected into a concave lens. Later, Hermann Helmholtz (1821-1894) would use this principle to develop the ophthalmoscope. Purkinje also studied dizziness and vertigo, and the effects of drugs such as digitalis and belladonna on the eye.

In 1838 German physiologist Ernst Wilhelm von Brucke (1819-1892) chose for his doctoral dissertation to disprove vitalism, the idea that a vital force was the basis of all life. He theorized that osmosis in living things was not related to a vital force but was measurable and explained by chemical and physical forces. Choosing the eye as his central subject, he compared the reflection of light from the background of eyes of different vertebrates and also studied stereoscopic vision, afterimages, and optical media. He showed diffuse reflected light could make the human eye glow, like the eyes of many animals. Helmholtz used this principle in his ophthalmoscope. Brucke's book Anatomical Description of the Human Eye (1847) became a standard work for physicians. A ciliary muscle in the eye that Brucke first described bears his name.

Johannes Peter Müller (1801-1858), a German physician, was a founder of experimental physiology. He taught and trained several great German scientists of the nineteenth century. He had many interests and wrote a famous Handbook of Human Physiology in 1841, which was a standard text for several generations of students. Sight was one of his many interests, and he determined that a sensation of light is caused by electrical stimulation of the optic nerve.

Helmholtz contributed greatly to knowledge about the sense of sight. While he was being trained as a military surgeon, he was fortunate to have Müller as his teacher. Müller was a vitalist, and Helmholtz sought to prove him wrong by investigating the principle that he called conservation of energy. He is credited with striking at the heart of vitalism when he showed that matter is neither created not destroyed. Helmholtz was also proficient in mathematics and physics and was one of the first to apply physics to life processes. He was the first to measure the speed of impulses and for ten years, from 1856-66, wrote his multivolume Physiological Optics.

In 1851, building upon knowledge of several predecessors, Helmholtz invented the ophthalmoscope. This devise for inspecting the interior of the eye consisted of a small mirror to direct a strong light into the eye. When the light reflects off the retina and back through a small hole in the ophthalmoscope, the physician can see a magnified image of the structures at the back of the eye. The ophthalmoscope revealed such structures as the optic disk, retina, blood vessels, macula, and choroid.

Albrecht von Graefe (1828-1870) is recognized as the father of modern ophthalmology. The son of the famous German pioneer of plastic surgery, Karl von Graefe (1787-1840), he dedicated himself to diseases of the eye. In 1850 he founded one of Europe's first eye clinics. Recognizing the importance of Helmholtz's ophthalmoscope, he promoted its use in his clinic. Working with the physicians at the University of Berlin, Graefe developed surgical procedures for many eye defects. In 1857 he removed a part of the iris, a procedure known as an iridectomy, to alleviate the pressure of glaucoma. Glaucoma results when pressure builds up from within the fluid of the eye, affecting the optic nerve. In 1860 he connected several types of blindness to an inflammation of the optic nerve, or optic neuritis. Concerned about cataracts, he developed a procedure for removing the lens in 1867. Graefe's name was given to a procedure he developed relating to Graves disease, a condition of hyperthyroidism where the eyes seem to bulge out. "Graefe's sign" is the failure of the upper lid to follow a downward movement of the eyeball when a person changes from looking up to looking down. Graefe wrote a seven-volume Manual of Comprehensive Ophthalmology from 1874-80.

Several physicians in different fields contributed to procedures for preventing disorders. Karl Credé (1819-1922), a German gynecologist, became concerned that mothers who had the sexually transmitted disease gonorrhea would infect their babies, who then became blind. Credé, looking at some of the work of Joseph Lister (1827-1912) and others using chemicals to kill contaminants, found that one percent silver nitrate dropped into the eyes would prevent gonorrheal ophthalmia. The procedure is still used routinely in hospitals today.

By the end of the century, ophthalmology was developing into a well-respected specialty. Allvar Gullstrand (1862-1930), a Swedish physician, was head of an ophthalmology clinic in Stockholm. In 1894 he became a professor of ophthalmology at the University of Uppsala. His greatest achievements were in the field of optics and his studies of the eye as an optical system. His work in astigmatism and how the eye accommodates though layers of crystalline lens led to an accurate model of the eye. He re-edited and updated Helmholtz's Handbook of Physiological Optics. Combining a microscope with a slit lamp, he was able to determine the exact location of a foreign particle in the eye. Gullstrand wrote many papers that pushed the knowledge of ophthalmology into the next century. He was awarded a Nobel Prize in medicine in 1911 for his investigations of the dioptics of the eye.

The nineteenth century saw an explosion of knowledge about the eye because of advances in clinical and experimental medicine. These developments transformed the oldest discipline in medicine into an exciting specialty.

EVELYN B. KELLY