Cerebral Hemispheres 2



Optograms: images from the eyes of the dead

March 3, 2019

On a cloudy fall morning in 1880, Willy Kuhne, a distinguished professor of physiology at the University of Heidelberg, waited impatiently for 31-year-old Erhard Reif to die. Reif had been found guilty of the reprehensible act of drowning his own children in the Rhine, and condemned to die by guillotine. Kuhne’s eagerness for Reif’s death, however, had nothing to do with his desire to see justice served. Instead, his impatience was mostly selfish—he had been promised the dead man’s eyes, and he planned to use them to quell a bit of scientific curiosity that had been needling him for years.

For the several years prior, Kuhne had been obsessed with eyes, and especially with the mechanism underlying the eye’s ability to create an image of the outside world. As part of this obsession, Kuhne wanted to determine once and for all the veracity of a popular belief that the human eye stores away an image of the last scene it observed before death—and that this image could then be retrieved from the retina of the deceased. Kuhne had given these images a name: optograms. He had seen evidence of them in frogs and rabbits, but had yet to verify their existence in people.

Optograms had become something of an urban legend by the time Kuhne started experimenting with them. Like most urban legends, it’s difficult to determine where this one began, but one of the earliest accounts of it can be found in an anonymous article published in London in 1857. The article claimed that an oculist in Chicago had successfully retrieved an image from the eye of a murdered man. According to the story, although the image had deteriorated in the process of separating the eye from the brain, one could still make out in it the figure of a man wearing a light coat. The reader was left to wonder whether or not the man depicted was, in fact, the murderer—and whether further refinements to the procedure could lead to a foolproof method of identifying killers by examining the eyes of their victims.

Optograms remained an intrigue in the latter half of the 19th century, but they became especially interesting to Kuhne when physiologist Franz Boll discovered a biochemical mechanism that made them plausible. Boll identified a pigmented molecule (later named rhodopsin by Kuhne) in the rod cells of the retina that was transformed from a reddish-purple color to pale and colorless upon exposure to light. At the time, much of the biology underlying visual perception was still a mystery, but we now know that the absorption of light by rhodopsin is the first step in the visual process in rod cells. It also results in something known as “bleaching,” where a change in the configuration of rhodopsin causes it to stop absorbing light until more of the original rhodopsin molecule can be produced.

In studying this effect, Boll found that the bleaching of rhodopsin could produce crude images of the environment on the retina itself. He demonstrated as much with a frog. He put the animal into a dark room, cracked the windows’ shutters just enough to allow a sliver of light in, and let the frog’s eyes focus on this thin stream of light for about ten minutes. Afterwards, Boll found an analogous streak of bleached rhodopsin running along the frog’s retina.

An optogram Kuhne retrieved from the retina of a rabbit, showing light entering the room through a seven-paned window.

Kuhne was intrigued by Boll’s research, and soon after reading about it he started his own studies on the retina. He too was able to observe optograms in the eyes of frogs, and he saw an even more detailed optogram in the eye of a rabbit. It preserved an image of light coming into the room from a seven-paned window (see picture to the right).

Kuhne worked diligently to refine his technique for obtaining optograms, but eventually decided that—despite the folklore—the procedure didn’t have any forensic potential (or even much practical use) at all. He found that the preservation of an optogram required intensive work and a great deal of luck. First, the eye had to be fixated on something and prevented from looking away from it (even after death), or else the original image would rapidly be intermingled with others and become indecipherable. Then, after death the eye had to be quickly removed from the skull and the retina chemically treated with hardening and fixing agents. This all had to be done in a race against the clock, for if the rhodopsin was able to regenerate (which could even happen soon after death) then the image would be erased and the whole effort for naught. Even if everything went exactly as planned and an optogram was successfully retrieved, it’s unclear if the level of detail within it could be enhanced enough to make the resultant image anything more than a coarse outline—and only a very rough approximation of the outside world.

Regardless, Kuhne couldn’t overlook the opportunity to examine Reif’s eyes. After all, he never did have the opportunity to see if optograms might persist in a human eye after death and—who knew—perhaps optograms in the human eye would be qualitatively different from those made in the eyes of frogs and rabbits. Maybe human optograms would be more accessible and finely detailed than he expected. Perhaps they might even be scientifically valuable.

Reif was beheaded in the town of Bruschal, a few towns over from Kuhne’s laboratory. After Reif’s death, Kuhne quickly took the decapitated head into a dimly-lit room and extracted the left eye. He prepared it using the process he had refined himself, and within 10 minutes he was looking at what he had set out to see: a human optogram.

Kuhne’s drawing of The image he saw when he examined Erhard Reif’s retina.

So was this the revolutionary discovery that would change ophthalmic and forensic science forever? Clearly not, or murder investigations would look much different today. Kuhne made a simple sketch of what he saw on Reif’s retina (reprinted to the right in the middle of the text from one of Kuhne’s papers). As you can see, it’s a bit underwhelming—certainly not the type of image that would solve any murder mysteries. It confirmed that the level of detail in a human optogram didn’t really make it worth the trouble of retrieval. Kuhne didn’t provide any explanation as to what the image might be. Of course any attempt to characterize it would amount to pure speculation, and perhaps the esteemed Heidelberg physiologist was not comfortable adding this sort of conjecture to a scientific paper.

This experience was enough to deter Kuhne from continuing to pursue the recovery of human optograms, and it seems like it would be a logical end to the fascination with optograms in general. The idea of using them to solve murders, however, reappeared periodically well into the 1900s. In the 1920s, for instance, an editorial in the New York Times critiqued a medical examiner who had neglected to take photographs of a high-profile murder victim’s eyes, suggesting that an important opportunity to retrieve an image of the murderer had been lost.

But as the 20th century wore on and our understanding of the biochemistry of visual perception became clearer, interest in optograms finally dwindled. Those who studied the eye were not convinced of their utility, and that opinion eventually persuaded the public of the same. It’s intriguing to think, though, how different our world would have been if optograms really had lived up to the hype. It certainly would have simplified some episodes of CSI.

Lanska DJ. Optograms and criminology: science, news reporting, and fanciful novels. Prog Brain Res. 2013;205:55-84. doi: 10.1016/B978-0-444-63273-9.00004-6.


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