4. The 1950s Electroretinogram
Studded with electrodes and wires, the Electroretinogram looks intimidating, but the device is actually useful, even today. Modern versions, however, are considerably more streamlined. Also called the ERG, the Electroretinogram tests to see how the retinas in the back of our eyes are working, and if there are any signs of disease. It can actually detect diseases like retinitis pigmentosa (RP), disorders that mimic RP, Usher Syndrome (a condition that affects vision and hearing), and scores of other diseases and disorders. For this test, patients are given eyedrops that dilate and anesthetize their eyes and their eyelids are propped open. An electrode attached to a contact lens is placed in each eye. An extra electrode is placed on the skin to act as a ground for the faint electrical signals produced by the retina. The patient is then tested with a series of red and blue lights to see how the retina reacts.
But electroretinography got its start in 1865 when Swedish physiologist Alarik Frithiof Holmgren began testing the procedure on amphibians. Researchers discovered that the stimulus provided by light could change the electrical potential of the creature’s eye. Then in 1877, Scotland’s James Dewar began testing the procedure on people. However, ERG wasn’t widely used until 1941, when Lorin Riggs, an American psychologist, introduced the contact lens electrode.