by Oliver Sacks
I saw a huge black opacity partly obscuring central vision, like an amoeba with pseudopodia. It seemed to expand, contract, pulse—but its edge was razor-sharp. I stuck a finger into it, and the finger vanished, engulfed as by a black hole. Going to the bathroom mirror, facing my reflection, I could not see my own head with the right eye—only my shoulders and the bottom of my beard. I could not see the tip of the pen when I wrote.
When I went out the next morning, I saw only the lower halves of people walking. I was reminded of how, in Joyce’s Ulysses, there is a Signor Artifoni who is characterized as “a pair of stout trousers” walking around Dublin. The streets were full of skirts and slacks, moving legs and hips with no upper halves. (A few days after this, the scotoma spread, and I could see only their feet.)
This, of course, is when I close the left eye. With both eyes, my vision is now remarkably “normal”—far more so than it has been for months, now that the right eye does not interfere with the left. It is out of the running, completely blind, at least so far as central vision goes. Oddly, this is a huge relief—I wish I had had it lasered months ago.
Stereo vision, however, now that I am mostly monocular, is quite compromised—completely missing in the upper half or two-thirds of my visual field, though partly intact in the bottom, where I retain some peripheral vision. So I see the lower halves of people in stereoscopic depth, while their upper halves are completely flat and two-dimensional. And, of course, as soon as I look at their lower halves, using what is left of my central vision, these become flat, too.
That first evening when I took off the bandage, I saw with my right eye a black blob, an amoeba. By the next day, this had settled into a darkness with the shape of Australia, complete with a little bulge in the southeast corner—I thought of this as its Tasmania. I was struck that first night by the fact that when I looked up at the ceiling, the blob disappeared, becoming so camouflaged that I could no longer be sure of its existence. I had to test to be sure, but it was still there—my black hole had become a white hole, had taken on the color of the ceiling around it. It was still a hole, and if I brought my finger from periphery to center, the finger would disappear as soon as it crossed the now-invisible margin of the scotoma.
I knew that the normal blind spot, which we all have, where the optic nerve enters the eye, is automatically filled in, so we are unaware of its existence. But the normal blind spot is tiny, whereas my own scotoma was huge, blotting out more than half of the entire visual field of the right eye. And yet, within a second or two of looking at a white surface, it could completely fill in, becoming white instead of black. The next day I tested this with a blue sky and found the same result. The scotoma became as blue as the sky, but this time I had no need to plot its margins with my finger, for when a flock of birds flew by, they suddenly disappeared into my scotoma, emerging on the other side a few seconds later—as if they had been cloaked in invisibility like a Klingon warship.
This filling in, I discovered, was strictly local, depending on a steady fixation of gaze. If there was a slight movement of the eye, the filling in dissipated, and the ugly black amoeba was back. Local, but persistent, for if I looked at a red surface for a few minutes and then at a white wall, I would see a large red amoeba (or Australia) on the wall, which would last about ten seconds before it turned white.
The blind spot, so called, does not just fill in color, it fills in patterns too, and I enjoyed experimenting with my own scotoma, testing its powers and limitations. It was easy to fill in a simple repetitive pattern—I started with the carpet in my office—though a pattern took a bit longer than a color, perhaps needing ten or fifteen seconds to duplicate. It would fill in from the edges, like ice crystallizing on a pond. The spatial frequency and fineness of detail in the pattern was crucial. My visual cortex had little trouble filling in fine-grained patterns, but coarser patterns were beyond it. So if, for instance, I stood two feet from a brick wall, my scotoma would turn brick red in color, but with no detail. If I stood twenty feet away, it would be filled in by perfectly respectable-looking brickwork.
Whether the brickwork was exactly the same as the original I could not be sure, but it was good enough to form a plausible simulacrum of the “missing” wall. I could be sure of exact replication only if I was gazing at absolutely predictable, repetitive patterns like chessboards or wallpaper. Once when I looked at a sky filled with fat woolly clouds, the pseudo-sky generated within the scotoma contained thin wispy clouds. I felt that my visual cortex was doing the best it could, perhaps by sampling or estimating the ratio of white cloud to blue sky, even though the actual shapes of the individual clouds were not right. I started to think of my visual cortex not just as a rigid duplicating device, but as an averaging device, capable of sampling what was presented to it and making a statistically plausible (if not photographically accurate) representation of it. I wondered if this was what cuttlefish and octopuses did when they camouflaged themselves, taking on the colors, patterns, and even textures of the seafloor or plants or coral around them—not exactly, but plausibly enough to fool both predators and prey.
I found that movement could also be filled in to some extent. If I looked at the Hudson River, slowly swirling or rippling with small waves, these too were reproduced in my scotoma.
But there were strict limits. I could not simulate a face, a person, a complex object. I could not fill in my own head in the mirror when it was blanked out by my scotoma. And yet here I made another discovery, one that filled me with wonder. Idly playing, scotomizing, one day, I looked at my foot with my right eye and “amputated” it with my blind spot, a little above the ankle. But when I moved my foot a little, wiggling the toes, the stump seemed to grow a sort of translucent pink extension with a ghostly, protoplasmic halo around it. As I continued wiggling my toes, this took on a more definite form until, after a minute or so, I had a complete phantom foot, a visual phantom equipped with the missing toes, which seemed to move with the movements I was making. The foot did not look wholly solid or real, for it lacked surface detail, the appearance of skin—but it was very remarkable nonetheless. A similar thing occurred with my hand if I scotomized it, “amputated” it above the wrist. I subsequently tried to do the same with others’ hands, but that did not work in the least. It was clear that my own foot or my own hand, my own movements and sensations, my own body image or intentions, were required.
After my lasering in June, I noticed that I could visualize my arms or other parts of my body in action, even when my eyes were closed, much more clearly and vividly than I had ever done before. “Seeing” my arms as I moved them seemed to attest to a heightened sensitivity or connection between the visual and the motor areas of the cortex—an intensity of communication or correlation between them unprecedented in my experience.
Another odd thing struck me within a day or two of the lasering in June of 2007. At one point, after gazing at the bookshelves in my bedroom for a few minutes, I closed both eyes and saw, for ten or fifteen seconds, the hundreds of books arrayed on the shelves in great, almost perceptual detail. This was not filling in but something quite different—a persistence of vision similar to what I had experienced in the hospital eighteen months earlier, when I seemed to see the washbasin so clearly “through” my eye patch.
Perhaps the loss of central vision in the right eye was equivalent to having it covered by a postoperative patch, in terms of depriving the brain of perceptual information. I had the sense that my visual cortex was now in a heightened or sensitized state, released to some extent from purely perceptual constraints.
Something similar happened a few days later, as I walked up to a crowded intersection full of bicycles, cars and buses, and people bustling in all directions. When I closed my eyes for a minute, I could still “see” the whole complex scene, full of color and movement, as clearly as if I had my eyes open.
I found this especially surprising, since I normally have very meager powers of visualization. I have difficulty evoking a m
ental picture of a friend’s face, or my living room, or anything at all. The persistence of vision I had experienced was richly, mindlessly detailed, much more so than any voluntary image. It was so detailed I could see the colors of cars and sometimes read their license plates, to which I had paid no conscious attention. Involuntary, unselective, unstoppable, the image seemed to me akin to photographic or eidetic imagery—but, unlike eidetic imagery, it had a very definite and brief duration, lasting ten or fifteen seconds and then fading.
At one point, as I was walking with a friend, I saw two men walking towards us, both wearing white shirts, brilliantly clear in the late-afternoon sun. I stopped and closed my eyes, and found that I could continue to watch them, seemingly still walking towards us. When I opened my eyes, I was startled to find that the men in white shirts were nowhere to be seen. They had, of course, walked past us, but I was so engrossed in what I “saw” with my eyes closed—an arrested fragment of the past—that I got a sudden shock of discontinuity. I say “arrested,” but what I saw in my mind’s eye had motion, too. The men were walking, striding, yet they remained in the center of my mind’s eye as they walked, without getting anywhere, as if on a treadmill. I had captured this bit of motion, like a film loop, which recycled in my mind even after they had gone. This had a paradoxical quality, like a snapshot of movement without any actual transit.
I rather enjoyed this persistence of vision, and Times Square, with its brilliant colored lights, its moving and flashing billboards, became a favorite place for testing it. The most potent stimulus of all was optic flow, a brisk stream of images past my eyes, which I could especially relish when I was a passenger in a fast-moving car.
I felt there was an analogy and perhaps a kinship between the filling-in phenomenon and the persistence of vision. Both came on strongly after the loss of central vision, though there had been intimations of both before. Both remained strong for two to three months in the summer of 2007 and then grew weaker (though they continue, in an attenuated form, to the present). “Filling in” seemed to me an inadequate term for a process which did not always confine itself to reconstituting a blind area but could go on to a sort of incontinent visual spread. (This, too, had been foreshadowed in those last, half-blind weeks before the June lasering, when faces spread and protuberated like monstrous, Francis Bacon faces.)
I experimented with this visual spread one day by gazing with my right eye at an old tree with a particularly exuberant and brilliantly green mass of foliage. Filling in soon occurred, so that the missing area turned green and textured to match the rest of the foliage. This was followed by a “filling out,” an extension of the foliage, especially towards the left, resulting in a huge lopsided mass of “leaves.” I realized how outlandish this had become only when I opened my left eye and saw the tree’s actual shape. I went home and looked up an old paper by Macdonald Critchley on types of “visual perseveration” which he called “paliopsia” and “illusory visual spread.”2 Critchley saw these two phenomena as analogous: one a perseveration in time, the other a perseveration in space.3
Here perhaps one has to use the word “pathological,” for one can hardly have a normal visual life if every perception gets extended and smeared in space and time; one needs restraint or inhibition, clear boundaries, to preserve the discreteness of perception.
Critchley’s patients had brain tumors or other cerebral disorders, whereas I had only retinal damage. Yet clearly I was also experiencing cerebral phenomena—I supposed that retinal impairment had led to some abnormal excitation in my visual cortex. Many years ago—I described this in A Leg to Stand On—I had an injury to the nerves and muscles in one leg that caused some strange cerebral symptoms similar to those of a parietal lobe disorder. When I wrote to the Russian neuropsychologist A. R. Luria about this, he spoke of “the central resonances of a peripheral disorder.” Now I was experiencing such a resonance in the realm of vision.
In June of 2007 I also had a sharp surge of hallucinations—apparitions that came out of the blue and had no relation to the external world—and this has continued, to some extent, ever since. Neurologists speak of simple or elementary visual hallucinations, as opposed to complex ones. In the simple ones, there are hallucinations of color, shapes, and patterns; in the complex ones, there may be figures, animals, faces, landscapes, etc. For the most part, I have simple ones.
Almost from the start, sparks, stripes, or blobs of light have appeared in my visual field, as well as complex patterns resembling alligator hide. I sometimes think that a wall is patterned or textured when it is not, and have to touch it to be certain whether the stippling I see is real.
I often see a multitude of little tufts, like tussocks of grass, all over my visual field, even with both eyes open. At other times there are checkerboards, usually black-and-white, but sometimes faintly colored. The apparent size of these checkerboards depends on where I am “projecting” them. If I look at a piece of paper six inches away, I might see a checkerboard on it the size of a postage stamp; if I look at the ceiling, it might appear to be a foot square; if I look at a white wall across the street, the checkerboard might be the size of a shop window. Some of my checkerboards are rectilinear, others are curvilinear, and some have an almost hyperbolic shape. Sometimes one checkerboard will undergo fission or multiplication, becoming a dozen smaller checkerboards, arrayed in rows and columns. Complex patchworks or mosaics are common, too, and seem to be variants or elaborations of the basic checkerboard patterns. These tend to switch from one to another in constant, kaleidoscopic change.
I also see tilings or tessellations composed of polygonal (often hexagonal) pieces, some flat and some three-dimensional, like honeycombs or radiolaria. Sometimes there are spirals or concentric rings, or radial patterns like filigreed doilies. Occasionally I see “maps”—maps of enormous, unknown cities, as might be seen at night from a low-flying airplane, with ring roads and radial spokes illuminated, looking like giant spiderwebs of light.
Many of these patterns are microscopically detailed. I see thousands of lights in my nocturnal cities. These images or hallucinations have greater clarity, are more fine-grained, than perception itself, as if my inner eye had an acuity of 20/5 rather than 20/20.
The most constant patterns (perfectly visible with both eyes open, and especially so if my visual field is otherwise blank) are sticklike or occasionally curved patterns resembling letters or numbers. Occasionally I recognize a 7 or a Y or a T or a delta, but for the most part they are unintelligible, like runes. They make me think of a child’s letter box, with letters spilled out at random and at all angles. These are rather faint and often have double lines, giving the impression of being incised like the lettering on a stone. These pseudo-letters and pseudo-numbers often flicker and form, dissolve and reform in fractions of a second, all over my visual field. Sometimes, if I am looking at a horizontal segment of a wall, the runes come in a row, like a frieze.
Most of the time, I am able to ignore them, as I ignore the tinnitus I have had for the past few years. But often in the evening, when the sights and sounds of the day lessen, I may become suddenly aware of these faint hallucinations. And often it is a visual emptiness—a ceiling, a white washbasin, the sky—which makes me conscious of the visual patterns and images continually chasing across my visual field. Yet these little hallucinations are interesting, in a way: they show me the background activity, the idling, of my visual system, generating and transforming patterns, never at rest.
THURSDAY, DECEMBER 20, 2007
I had been feeling fairly relaxed about my tumor—it seemed relatively indolent and contained, and Dr. Abramson had said it was rare for ocular melanoma like mine to metastasize. But on Monday (the seventeenth, two years to the day since my tumor presented itself) I observed, in the gym, a roughly circular black spot the size of a dime on the skin just below my left shoulder. I was startled and frightened: the spot was jet black in color, with a clear border, and slightly raised; it looked nothing like an ordina
ry bruise. Was it, more ominously, the start of a skin melanoma, metastasized from the tumor in my eye?
When I showed the spot to Mark and Peter, who came for dinner tonight, both of them looked startled and worried. “It looks bad, very dark,” Mark said. “I think you should get it checked within twenty-four hours.” It did not, he added, look like a melanoma; but it did not look like anything he had ever seen before. Christmas holidays are upon us, as they were in ’05, and this means that I should get it looked at tomorrow; otherwise it may have to wait until the New Year. I fear I will obsess about it, get myself into a near panic, if this cannot be clarified straightaway. I feel agitated now … I think I may have to sedate myself.
FRIDAY, DECEMBER 21, 2007
The dermatologist, Dr. Bickers, a kind, sensitive man, very knowledgeable, too—realizing my anxiety, worked me into his schedule today. He looked at my arm and the rest of my skin, saw nothing amiss. The blackness, he said, was just a little bleeding into one of the brown spots that increasingly mottle one’s skin with age. Probably I had bumped into something; the blood would clear in a couple of days. I am greatly relieved—I would have gone mad waiting until January to have it checked.
For a decade or so before my melanoma, I had been an active member of the New York Stereoscopic Society; I had enjoyed playing with stereoscopes and stereo illusions since childhood. Seeing the world in depth always seemed as natural, as integral to my visual world as color vision. It gave me a sense of the solidity of objects and the reality of space—the wonderful, transparent medium in which they resided. I was keenly conscious of how my visual world instantly collapsed if I closed one eye and reexpanded the moment I opened it again. Like many of my fellow members of the Stereoscopic Society, I seemed to live in a deeper world, visually, than most people.