Refractive errors have been with primates and modern man since we emerged from the trees onto the African Savannah about 3 million years ago.
Human eyes with no refractive errors are indeed rare. However, most of these refractive errors are small and clinically insignificant.
With the small pupils found during most daylight activities, the increased depth of focus can effectively “mask” a large number of these refractive errors. Unlike the big cats and other nocturnal carnivores in Africa, we function much better during daylight. Contrary to popular belief and to the disappointment of those who sell glasses and contact lenses, uncorrected refractive errors are rarely the cause of headaches, even headaches that seem to localize in, around, or behind the eyes [Greater Occipital Neuralgia is a common cause].
Eyeglasses with colored lenses. France, c1850.
In his scholarly book, “Spectacles and Other Vision Aids,” J. William Rosenthal, MD has chronicled the invention of what look like “spectacles” to the late 1200’s A.D. [circa1280]. The first spectacles originated in Italy. The name of the inventor is unknown. The original design for spectacles included a frame to hold the right and left spectacle cell had a rivet [swivel motion] attached to a small strut to hold the two lenses together. A space was made between them to slide over the nose. The lenses were probably made of clear quartz [pebble quartz] or beryl [sea green stone of beryllium aluminum silicate] and due to their curved surface, they demonstrated some ability to magnify an object of regard.
Polished optical quality glass made from hardened molten silicate with either lead or flint added for clarity would not be available until the 1600’s. The magnification of these early spectacle lenses was crude guesswork at best, not very clear, and the two lenses probably were of different dioptric power. They probably were only of value to people who lived long enough to become presbyopic, or “old man’s vision,” and were used mainly by scribes and monks in churches. The life span of a person in the late 1200’s is estimated to be no more than 35 years. There weren’t a lot of folks who lived long enough to become presbyopic. Of course, if you were myopic (“nearsighted,” sighted for near) your distance vision was always a problem, but you could see close up without any need for magnification. I’ll bet that most of the artisans that did the paintings on the walls inside the great Egyptian tombs were nearsighted.
Gold plated visual glasses, Benjamin Martin, England, 1775-1820.
Johann Gutenberg invented the printing press in the mid 1400’s. This revolutionized the world of printed material. Most books in the early days of the first millennium were written on silk, parchment or vellum [processed sheep, goat or calfskin]. These materials had replaced the dried papyrus leaves that the early Egyptians, Greeks, and Romans favored. In 105 C.E., bamboo pulp was made into paper by Cai (Ts’ai) Lun in China. This invention was a monumental breakthrough, and the name Cai (Ts’ai) Lun is well-known in China.
By the 17th century in Europe, the monocular that is a single lens, was the preferred reading aid and it was usually hung around the neck or nestled in a coat pocket. Up to this point, the only refractive correction available was for people who were presbyopic [if they lived long enough] or that rare person who was significantly “farsighted” (hyperopic).
This term implies that a patient’s vision is good at “distance.” However, most clinically significant farsighted people can’t see well at distance or close up! The discovery of the physiologic process known as accommodation [changing focus from distance to near] was elegantly quantified by Frans Cornelius Donders (1864), who developed a scale of values of accommodative amplitude based upon one’s age. Most farsighted young people have a large amplitude of accommodation and can still see well at distance and near until they reach early middle age and then may need glasses for distance or near vision.
I was always surprised to see patients with relatively large uncorrected hyperopic refractive errors who were either totally asymptomatic or who would only occasionally complain of some difficultly with near vision during the early evening hours. The term “eye strain” is actually a myth and should be eliminated. Generalized fatigue, stress and keeping the eyes open all day leads to some drying of the ocular surface which causes some ocular discomfort. A good deep tissue neck massage can do wonders.
Spectacles, USA, 1940-1945.
The two refractive conditions that were not addressed by the early spectacle makers were “astigmatism” and “myopia.” The concept of astigmatism was put forth by Thomas Young around 1800 and the first “toric” (astigmatic, two radii of curvature usually 90 degrees apart) lens was produced around 1827. Confucius described the phenomenon of myopia (nearsightedness) around 500 B.C.E., and there is speculation that he had access to a concave lens to correct myopia. This should not be surprising since the Chinese and other Asian countries have higher incidences of myopia. Lenses to correct myopia [concave lenses] probably appeared around 1700.
“The Greatest Salesman in the History of the World,” was probably Benjamin Martin in London in the early 1700’s. He convinced everyone that to avoid “eye strain” [asthenopia] one should wear corrective lenses in a frame with a rather wide and thick edge to “block extraneous light.” When looking straight ahead your eyes stay in the optical center of the lens. However, when you look to the side or up/down you induce a prism effect. With his glasses, called “Martins margins,” you had to turn your head to see to the side or up/down. This wide and thick circular edge to the frame produced a “ring scotoma,” a blind area, especially noticeable in the temporal visual field. He also recommended that a “tea-colored tint” be added to the lenses for comfort at an additional charge, and he laughed all the way to the bank. The public, especially the wealthy in London, bought into this salesmanship hook, line and sinker.
Carved tortoiseshell eyeglasses, China, 1875.
The modern era of spectacles is here and with a price tag to boot. I always tell friends that before any eye care provider tells you to change your glasses, please have them show you with a vision chart what vision you have out of your current glasses and then show you the proposed improvement in vision with the new expensive spectacles. This can be done very quickly on most modern refraction devices such as the automated phoropter. If they can only appreciate a small improvement, then the old spectacles are close enough. The decision then becomes an economic and fashion decision. As an ophthalmologist, I can easily spot a patient with an evolving cataract a mile away with a pair of binoculars. If a patient approaches me with a brown bag holding 11 pairs of glasses and he's looking for pair number 12, I don't do it!
In the future will we still need glasses? The answer is a resounding yes! However, the advances in refractive surgery and cataract surgery have dramatically reduced the need for spectacles. In developing countries that do not have access to the most modern advances in ophthalmic microsurgery, glasses will continue to be alive and well. In these situations, adjustable spectacles can be a solution. They work by turning a dial on the temporal side of the frame can be fit for patients who are hyperopic or myopic. In the early days of the Renaissance, eyedrops and potions were frequently prescribed to “strengthen the eyes.” This of course was quackery. However, some new data suggests that we might be able to delay the onset of presbyopia by using a special eye drop that can alter the refractive power of the lens of the eye if used once per day in each eye. And a thousand years from now, when they look into the casket of someone who passed away in the 21st century, they will find two small clear round acrylic lenses. The archeologist will exclaim, “Oh that’s what they did back then to help people see after cataract surgery. We see it all the time in these specimens. That was, of course, before the bionic eye was perfected!”
Horn split bridge eyeglasses England, c1650.
As a final note, let’s consider correcting refractive errors in reverse. Let’s say that the only way to correct a modest refractive error was with a surgical procedure like Lasik or cataract surgery. Then one day a brilliant thinker suggested that we can correct refractive errors without going to the operating room. A thin little disc of hard plastic or of a soft hydrogel material could be placed on the cornea of the eye to achieve good vision. Miraculous! Then several decades later another brilliant thinker proposed another new idea. Instead of putting an uncomfortable foreign object on your cornea, we could achieve good vision by placing corrective lenses in a structure that was supported by your nose and held in place by two long arms that landed above your ear lobes and anchored the device to your face so they would not fall off. Brilliant idea! The world would be changed forever.
All images courtesy of the Truhlsen-Marmor Museum of the Eye, Harriet and J. William Rosenthal, MD Collection.