Promising nuggets in early scientific research can quickly take hold of the public imagination and continue to spread well past their sell-by date, a lesson we are all learning the hard way during this pandemic. But this phenomenon is not new. Let me ask you this: do you believe the last thing someone sees before they die gets imprinted on their retinas? It turns out this idea is a myth... mostly.
The eye is often compared to a camera, and the retina at its back can be thought of as a sort of photographic film that can capture images and transmit them to the brain. The comparison is simplistic and when all you have is a hammer, all you see are nails. In 1837, the first photographic process (known as a daguerreotype) was invented, followed thirteen years later by the ophthalmoscope, a device that allowed doctors to see through a patient’s pupil and inspect the back of their eye. So it makes sense that, in the following decades, the eye was expected to be a sort of biological camera. Thus the persistent rumour in the Victorian era that a slain person’s eyes could capture their murderer’s likeness.
There is a grain of scientific truth to this idea that became formally known as “optography” (meaning “writing of the eye”). The rumour was already circulating when Franz Boll, a German scientist interested in the functioning of living bodies and their tissues, observed for the first time that a pigment at the back of the eye would turn white when exposed to light before returning to its original colour in the dark, a phenomenon known as photobleaching. He figured this fascinating process had something to do with how the eye sees.
Subsequently, another German scientist, Willy Kühne, confirmed Boll’s research and made new observations of his own: that this pigment was indeed stable after death as long as it was not exposed to light; that this photobleaching was due to incoming light changing something about the chemistry of the back of the eye; and that sometimes, this process could yield a recognizable image. Kühne was working with frogs, and one of them was placed in front of a gas lamp for 14 hours. When Kühne looked at the frog’s retina after death, he could see an image of the flame! Fans of animal welfare beware: Kühne’s experiments involved paralyzing his frogs with the poison curare, cutting away their translucent third eyelids (known as the nictitating membrane), stuffing a paper ball into their mouth, and placing them in front of a flame for a couple of hours. Then off came the eyes to be scrutinized by the scientist.
Kühne managed to test this phenomenon in humans once. A man who had drowned his youngest children was to be beheaded by guillotine. Kühne was present at the execution: he quickly grabbed the decapitated head, removed its eyes in a dimly lit room, and extracted the retinas. There, Kühne witnessed a human “optogram”: a tiny picture, 2 mm by 3-4 mm in length, looking like a Fez hat with two bites taken out of it. It remains unclear what this image was supposed to represent, though it was some hazy record of the last thing the man saw before losing his head.
From paralyzed frogs to Jack the Ripper
The idea that a murder victim could nab the perpetrator from the great beyond with help from the emerging science of ophthalmology was immensely seductive. In a last-ditch attempt at capturing an image of Jack the Ripper’s true face, police in 1888 took close-up photographs of the eyes of who is believed to be the Ripper’s fifth and final victim, Marie Jeanette Kelly, to no avail. Journalists would sometimes chastise the police for not resorting to forensic optography, such as in the 1920 gunshot murder of wealthy philanderer Joseph Bowne Elwell, when a New York Times editorial criticized the medical examiner for not photographing the victim’s eyes to identify his murderer. The legendary power of the eye’s last sight in damning a murderer was also popularized by famous novelists like Jules Verne and Rudyard Kipling and was later refashioned by early science fiction writer into the “necroscopic brain-scan,” in which the last sequence from a person’s life can be extracted from their brain and replayed like a movie.
Reassuringly, the myth that retinas can be used by crime scene investigators has pretty much always travelled side by side with a reasoned scientific critique of this idea. Kühne himself, as he was subjecting his frogs to a horrifying prelude to A Clockwork Orange, expressed his disdain in 1878 that his discovery was being twisted into a “popular interpretation.” He could not work out how his findings could be used by police officers to identify murderers: these optograms could only be seen in very precise circumstances. First, they required an object that was simple and with high contrast, and a human face is too complex. Then, the eye had to fix this target for a very long time. Finally, the eye had to be removed immediately after death and its retina had to be hardened and fixed to even have a chance of obtaining some sort of image that would be small, partial and not particularly sharp. Not exactly on par with DNA evidence.
Modern fiction occasionally continues to prop up optography to the level of a crime-solving technique on shows like Fringe and Doctor Who. Animal experiments in the Victorian era certainly contributed to our understanding of the biochemical processes behind our sense of sight, but we should be wary of naive extrapolations. There is more than meets the eye when it comes to retinal images.
Take-home message:
- Optography is the idea that we can identify a person who committed a murder because the victim’s eyes recorded that image, a claim that is essentially not true
- The idea behind optography seems to have started in the 1800s and was thought by some to have some support in the animal experiments conducted by German scientists
- A small and ambiguous image can indeed remain on the back of the eye following death but only in exceptional circumstances when the victim looked at the object for a long time and their eyes were immediately examined after death
