The history
2,600 years from pushing a cloudy lens aside with a needle to lasers, plastic lenses and a billion people still waiting for glasses.
For most of history people argued about how we see at all: did rays leave the eye, or enter it? Ibn al-Haytham showed that light comes in, Kepler found the upside-down picture on the retina, and scientists slowly learned how three kinds of cone make colour and how a single photon starts a signal. At the same time, spectacles, eye charts, contact lenses, plastic lenses and lasers turned that knowledge into sight for millions, from London to Madurai.
c. 600 BCE (attributed)
Described cataract couching
Sushruta Samhita, India
1011–1021
Showed that light enters the eye
Ibn al-Haytham, Cairo
c. 1286
Reading glasses
Unknown craftsmen, Pisa, Italy
1604
Explained the image on the retina
Johannes Kepler, Prague
1851
Ophthalmoscope
Hermann von Helmholtz, Germany
1862
Standard eye chart
Herman Snellen, Utrecht
1888
Contact lens
Adolf Eugen Fick, Zurich
29 November 1949
Intraocular lens implant
Harold Ridley, London
1990
LASIK on a sighted eye
Ioannis Pallikaris, Crete
600 BCE – 1760
Early surgeons in India and Europe treat cataracts, while Greek thinkers imagine rays shooting out of the eye.
600 BCE
c. 600 BCE (attributed)
The Sushruta Samhita, an ancient Indian surgical text, describes couching: a needle pushes the clouded lens down and out of the line of sight. Scholars date the text in layers, some of it centuries later than Sushruta himself.
Why it mattered. It is one of the oldest known descriptions of eye surgery, and couching was used for cataract for over two thousand years.
300 BCE
c. 300 BCE
Euclid's Optics treats vision with straight lines drawn from the eye to what it sees. Like many Greek thinkers he imagined the rays going out of the eye, not in.
Why it mattered. His geometry of straight rays survived, even though the direction turned out to be backwards.
1747
8 April 1747
Instead of pushing a cataract aside, the French surgeon Daviel opened the eye and removed the cloudy lens. He presented his method to the Royal Academy of Surgery in 1752.
Why it mattered. Removing the lens, rather than couching it, is the basis of every cataract operation today.
1000 – 1700
Ibn al-Haytham shows light enters the eye, Italian craftsmen make glasses, and Kepler finds the upside-down image on the retina.
1011
1011–1021
In his Book of Optics, written in Cairo, Ibn al-Haytham argued with experiments that we see because light from objects enters the eye, not because the eye sends out rays. He studied the anatomy of the eye and the camera obscura.
Why it mattered. It set optics on the path of testing ideas with experiments, and shaped European science for centuries.
1286
c. 1286
Convex lenses in frames, to help older people read, appeared in northern Italy. A sermon given in Florence in 1306 by the friar Giordano da Pisa said the art of making them was not yet twenty years old.
Why it mattered. Spectacles were among the first tools to fix a failing part of the human body, and they gave scholars decades more of reading.
1604
In a book on optics, Kepler worked out that the lens of the eye focuses light into an upside-down picture on the retina, and that the retina, not the lens, is where seeing starts. He also explained how concave and convex lenses help short and long sight.
Why it mattered. It is the camera model of the eye we still use today.
1619
1619 and 1626–1630
Scheiner described the eye's anatomy and refraction in his book Oculus (1619). In a later book, Rosa Ursina, he reported cutting away the back coats of animal and human eyes so he could see the tiny inverted image on the retina itself, confirming Kepler.
Why it mattered. It showed with the eye itself that the image on the retina really is upside down.
1660 – 1870
Newton splits light, Young proposes three receptors, Helmholtz looks inside a living eye and Snellen measures sight.
1672
1666–1672
With prisms, Newton split sunlight into a spectrum and recombined it into white. He reported the work to the Royal Society in 1672 and later wrote it up in his book Opticks (1704).
Why it mattered. It showed that colour is in the light and in how we sense it, the starting point for colour vision science.
1794
31 October 1794
Dalton, a chemist, noticed that flowers other people called pink looked blue to him. He described his colour vision to the Manchester Literary and Philosophical Society, and for a long time colour blindness was called Daltonism.
Why it mattered. It was one of the first careful scientific reports of colour vision deficiency.
1802
Young proposed that the eye does not need a receptor for every colour: three kinds, sensitive to different parts of the spectrum, are enough. In the 1850s Hermann von Helmholtz developed the idea further, so it is called the Young–Helmholtz theory.
Why it mattered. It is the three-cone theory of colour, confirmed by measurements more than 150 years later.
1819
The Madras Eye Infirmary opened in 1819, the second eye hospital in the world after Moorfields in London (1805). It became the Regional Institute of Ophthalmology in Egmore, Chennai.
Why it mattered. It began a long tradition of eye care and training in India.
1851
Helmholtz built the ophthalmoscope, a mirror that sends light into the eye and lets a doctor look along the same path to see the retina, its blood vessels and the optic disc.
Why it mattered. For the first time doctors could see diseases of the retina and optic nerve in living patients.
1862
Snellen designed letters on a grid, each part one-fifth of the letter's height, so that sharpness of sight could be measured and compared. His chart, with the big E at the top, is still used around the world.
Why it mattered. It turned "I can't see well" into a number, like 6/6 or 20/20.
1864
Donders' book On the Anomalies of Accommodation and Refraction of the Eye explained myopia, hyperopia, astigmatism and presbyopia and how to measure and correct them with lenses.
Why it mattered. It made fitting glasses a science.
1870 – 1970
Scientists find visual purple, draw the retina's cells and work out how light becomes a nerve signal and a picture in the brain.
1876
Boll saw that the reddish-purple colour of a frog's retina faded in bright light and came back in the dark. The pigment, rhodopsin, was then studied by Wilhelm Kühne.
Why it mattered. It was the first clue to how light is caught by the eye's chemistry.
1892
1892–1893
Using a silver stain, Cajal drew the retina's layers of rods, cones, bipolar cells and ganglion cells and argued that signals flow from one cell to the next in a set direction.
Why it mattered. His drawings are still used to teach how the retina is wired.
1911
Gullstrand won the Nobel Prize in Physiology or Medicine for his work on the dioptrics of the eye, how the cornea and lens bend light. His schematic eye is an ancestor of the model used in this box.
Why it mattered. It made the eye a precise optical system that could be calculated.
1959
Recording from single cells in the visual cortex, Hubel (from Canada) and Wiesel (from Sweden) found cells that respond to edges and lines at particular angles. They shared the 1981 Nobel Prize.
Why it mattered. It showed how the brain builds pictures out of simple features from the eyes.
1967
Wald showed that vitamin A forms retinal, the part of rhodopsin that changes shape when it catches light. Granit and Hartline showed how the retina's cells turn light into nerve signals.
Why it mattered. It explained the first step of vision, from photon to signal.
1885 – 2000
Contact lenses, plastic lenses inside the eye, laser surgery and mass cataract programmes in India bring sight back on a huge scale.
1888
Fick made a glass shell that sat on the white of the eye over the cornea, tried it on rabbits, then on himself and a few volunteers, and published it as a "Contactbrille".
Why it mattered. Contact lenses now correct the sight of well over a hundred million people.
1949
29 November 1949
Ridley noticed that splinters of acrylic plastic from aircraft canopies sat quietly in wounded RAF pilots' eyes. He designed an acrylic lens and implanted it after removing a cataract. Many doctors doubted him for years.
Why it mattered. Intraocular lenses are now fitted in millions of cataract operations every year.
1976
After retiring as a government eye surgeon, Dr Venkataswamy opened an 11-bed eye clinic. Aravind Eye Hospitals grew into one of the world's largest eye care providers, doing hundreds of thousands of surgeries a year with most poor patients paying little or nothing.
Why it mattered. Its high-volume, low-cost model has been copied around the world.
1976
India launched the National Programme for Control of Blindness, with cataract surgery at its heart. It is now the National Programme for Control of Blindness and Visual Impairment and supports millions of cataract operations every year, many of them free.
Why it mattered. It turned cataract surgery into a public health campaign across a vast country.
1988
17 May 1988
Bath patented the Laserphaco Probe, a device that uses a laser to break up a cataract before it is removed. She was the first Black woman doctor to receive a US patent for a medical invention, and co-founded the American Institute for the Prevention of Blindness.
Why it mattered. Her work helped make cataract surgery gentler and campaigned for eye care as a right.
1990
1989–1990
Pallikaris lifted a thin flap of cornea and reshaped the tissue beneath with an excimer laser. He first tried it on a blind eye in 1989 and on sighted eyes in 1990, and named it LASIK.
Why it mattered. Changing the cornea's curve changes the eye's main lens, so millions no longer need glasses.
2000 – today
Short sight spreads fast and billions still lack care, so eye health becomes a worldwide goal.
2016
A study pooling data from around the world estimated that about 23% of people were short-sighted in 2000 and projected about 50%, nearly five billion people, by 2050, driven by more near work and less time outdoors.
Why it mattered. It made myopia a global public health concern, especially in children.
2019
The first WHO World report on vision estimated that at least 2.2 billion people have a near or distance vision problem, and that at least 1 billion of these could have been prevented or have not been treated.
Why it mattered. It showed that most poor sight is caused by things we already know how to fix, such as cataracts and missing glasses.
2021
2019–2021
Pooling Indian studies, researchers found that myopia in city children aged 5 to 15 rose from about 4% in 1999 to about 21% in 2019, and projected about 48% by 2050.
Why it mattered. Short sight is becoming one of the most common health problems for Indian children.
By the numbers
Estimates and projections from Holden et al. (2016): myopia is expected to rise from about 1 in 4 people to about 1 in 2 by 2050. Values after 2016 are projections, not measurements.
Did you know?
Your blind spot is about 5 degrees wide: room for about ten full Moons side by side.
The picture on your retina is upside down. Your brain turns it the right way up.
An eyeball just 1 mm too long makes you about 3 dioptres short-sighted.
A rod can respond to a single photon of light.
The fovea packs up to about 200,000 cones into each square millimetre.
The people
c. 965 – c. 1040 · Physicist and mathematician · Basra, worked in Cairo
Showed with experiments that vision is light entering the eye.
1571 – 1630 · Astronomer · Germany
Explained the upside-down image on the retina and how glasses work.
1773 – 1829 · Physician and physicist · England
Proposed three colour receptors; also explained astigmatism and accommodation.
1766 – 1844 · Chemist · England
Described his own red–green colour blindness in 1794.
1821 – 1894 · Physician and physicist · Germany
Invented the ophthalmoscope and explained how the lens changes shape to focus.
1834 – 1908 · Ophthalmologist · Netherlands
Designed the eye chart still used today.
1852 – 1934 · Neuroscientist · Spain
Drew the retina's cells and how they connect.
1906 – 2001 · Ophthalmologist · England
Implanted the first intraocular lens in 1949.
1918 – 2006 · Ophthalmologist · Tamil Nadu, India
Founded Aravind Eye Hospitals to end needless blindness.
1942 – 2019 · Ophthalmologist and inventor · USA
Invented the Laserphaco Probe for cataract surgery.
Where it happened
Sources
Dates marked “c.” are approximate, and historians sometimes disagree about who was first. If you spot a mistake, tell us.
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