How I See the World

I hate looking people in the eye when I talk to them. Don’t get me wrong -- I think eye contact is the best indication to a person that I’m paying close attention to what he or she is saying. I’m not an especially shy person or anything; I’m just anticipating the moment when the other person suddenly stops talking mid-sentence, peers closely into my face and exclaims, “Hey! Did you know …”

Yes. Yes, I know. I know my eyes “twitch.” I know they “shake.” They’ve done that for as long as I can remember.

I have what is medically termed congenital idiopathic lateral nystagmus. Nystagmus (pronounced nih-STAG-muss) is an ocular motility disorder that is characterized by involuntary eye movements. Nystagmic eyes shake back and forth or rotate due to some malfunction in the visual machinery. My particular brand of nystagmus is “congenital” because it was manifest from birth, “idiopathic” because the cause is unknown, and “lateral” because the movement is horizontal. When I was growing up, I never knew what the twitching actually was, much less that it had a name. I didn’t know how to explain it to those who felt compelled to point it out to me, and I had difficulty dealing with the insensitive responses, intended or not, of both adults and other kids to this little-known condition. To complicate things further, the phenomenon sometimes extended to the unconscious shaking of my head.

I remember one particular day in my sixth grade Social Studies class when Mr. Skinner was lecturing with his usual boundless enthusiasm on some subject long since forgotten. In his practiced mode of engaging the class, he solicited everyone’s opinions: “What do you guys think?” Looking at me, he added offhandedly, “I know that Winnie disagrees; she’s been shaking her head the whole time I’ve been talking.” The entire classroom erupted in laughter, and Mr. Skinner was baffled: “What’s so funny? What did I say?” He turned towards me for an explanation, but I was staring down at my desk, hoping alternately that my face wasn’t as red as it felt and that I wouldn’t embarrass myself further by crying.

In high school, a friend told me that he was afraid to make a class presentation because of my consistently negative response to everyone else’s. He was intimidated by the head shaking. I could only apologize and explain that my head just does that. For the rest of the term, I self-consciously rested my head in my hands to keep its movements in check.

The head shaking seems to have diminished with time, but people still don’t know what to make of the eye twitching. When they notice it, they inevitably ask two questions: “Can you make them do it again?” and “Does everything you see shake too?”

The first question justifies my immediate defensiveness at any mention of my eyes. I feel like a spectacle, a performer in a circus sideshow. Worse yet is when, on seeing the shaking again, a person responds with “Whoah, that’s really weird,” or “What’s wrong with your eyes?” Yes, thank you for confirming that I am a freak. Yes, I know I am defective. I can’t help but wonder what sort of response this person would get if he or she said the same thing to someone who was physically disfigured.

Oddly enough, the answer to the second question is an emphatic “no.” I’ve never been able to tell when my eyes were shaking. This perhaps can partially explain my shame and humiliation every time someone points it out; it comes as a rude surprise. On the other hand, the fact that I can’t detect the physical motion of my eyes with the image I perceive suggests some fascinating things about the brain and the way vision works.

None of this occurred to me when my optometrist first identified the condition for me by name during a routine eye exam a couple of years ago. I just wanted to know what it was exactly. As I found out more about nystagmus, however, I came to understand its effect on how I see everything.

In Life: The Science of Biology, William Purves and his colleagues explain that in a vertebrate visual system such as the human’s, light is channeled through the eyes to the photosensitive layers of the retina at the back of each eye. The retina contains many photoreceptors, cells whose responses to contact with light translate into signals that are sent to the brain. These photoreceptors are not evenly distributed across the retina, however; the density is greatest at the fovea, making this the area of greatest visual acuity. When the eyes fixate on or track an object, the image falls upon the fovea.

Nystagmus is the result of a malfunctioning in the eyes’ movement mechanisms – specifically, the eyes’ inability to foveate – that is, to maintain an image on the fovea. According to the British Royal National Institute for the Blind (RNIB), congenital nystagmus can be caused by disorders like albinism or cataracts. Or, as in my case, it can have no known cause at all. My brand of nystagmus also happens to be genetic: both my father and my older cousin Irene have the same condition. Nystagmus can also be acquired later in life as a symptom of anything from a stroke to a mere blow on the head. Though the prevalence of this condition is not accurately known, it is estimated that as many as one in 1,000 individuals are affected. There is possibility of treatment, as physical therapy and surgical therapy can lessen the severity of the condition. The results are limited, however, and there is no cure.

Most people don’t ever notice the shaking in my eyes. One of the more interesting features of nystagmic eyes is the “null point” of vision, or the position where vision is most acute and the shaking is least severe – imperceptible, even. I’m lucky in that respect: my null point happens to be in the center of my vision where I focus straight ahead. I try to remember to make eye contact with people head-on to avoid needlessly demonstrating my freaky abilities. My cousin’s null point, however, is located in the right-hand corner of her eyes, so she adopted a head posture to allow for sharper fixated vision and better concentration: she watches TV out of the corner of her eye – her head turned away from the screen -- and often thinks with her head cocked to one side.

The RNIB confirms that nystagmus causes many of my other previously unexplainable visual problems and related physical phenomena. The head shaking, for example, helps me to concentrate: the head tries to compensate for the motion of the eyes. This is still evident when I read; I’ve been told that I look like I’m reading really fast since my head scans quickly back and forth across the page. I also used to think that my tendency to hold books close to my face when I read could be attributed to my near-sightedness, but I’ve since realized that pages of small text just prove too great an obstacle to foveation. The proliferation of letters – especially the high-contrast black type on white paper – provides too much visual stimulation. In a 1997 study, Eggert, Straube, and Schroeder found that nystagmic individuals had lower thresholds for perceiving motion – most likely the result of the eyes’ failure to track properly. This explains why it always seems to take me overly long to locate the mouse pointer on a computer screen. Or why I’m never able to find someone from across a department store. Or why I find televised sporting events so boring – I just can’t follow that damn ball. My eyes have trouble fixating on one object when there’s all this other stuff in my field of view. I think I’m beginning to understand my father’s predilection for big-screen TVs and unwieldy computer monitors.

While understanding the effects and implications of nystagmus certainly made explaining the twitching to others somewhat easier, it didn’t really make me feel any more normal. In fact, it wasn’t until my friend Mark, a graduate student in neurophysiology, pointed out the most interesting aspect of my nystagmus – that I couldn’t tell my eyes were moving – that I thought about the condition with less shame and more fascination.

Everyone’s eyes actually oscillate involuntarily to a small degree when fixating; the Applied Vision Research Unit at the University of Derby (U.K.) explains that these motions, called microsaccades, keep the photoreceptors in the fovea stimulated so that they continue to transmit information to the brain. Without the microsaccades, a stable image would fade and eventually disappear from view. No one is able to detect these minute vibrations because the brain compensates for them, performing the necessary adjustments to produce a steady image.

Mark is amazed that my vision is equally stable, especially since the shaking of my own eyes is visible to other people. He theorizes that my brain “somehow manages to do crazy computations” to eliminate the shaking in the image I actually perceive, that if one were to measure what was actually going on in the photoreceptors, one would see staggering amounts of neural activity. The more I think about this, the more compelling it seems. I’d thought that my eyes filtered in the outside world to my brain, when it is actually the brain itself that does most of the filtering. I suppose this just confirms that, in a manner of speaking, the perception of reality really only depends on state of mind.

My brain’s ability to compensate is part of a physiological phenomenon scientists call “plasticity.” Plasticity, as Neimeyer and Starlinger confirmed in their 1981 study, is the reason why blind people can hear better than those with normal sight. It also explains why amputees often experience “phantom sensations” in the amputated extremity: as the Macalester College website, “Phantom Limbs” states, this is a “subjective sensation” independent of external factors.

Not that long ago, scientists theorized that the brain was hardwired – that specific parts of the brain received and processed external stimuli according to the bodily origin of the sensation. That is, these scientists thought that one part of the brain would only correspond with tactile information from the hands and would be unable to handle visual information. Sensations from different fingers would map to distinct sections of the neural cortex. However, the famous 1995 Silver Springs study found that, in monkeys whose brains had been disabled for arm sensations, the part of the brain corresponding to the face eventually showed responses to stimulus to the arms. The damaged area is supplanted by a different, undamaged part, and functionality is restored. The brain learns to fix what the body cannot.

To be honest the old anxieties still linger; feeling empowered by the neural abilities doesn’t make eye contact any less daunting. Now, I try to head people off at the pass, broaching the subject myself in a casual, light-hearted way. I explain the workings behind the nystagmus, at the same time reassuring myself that I am not a freak, that it is only a minor quirk. I still know I will never be a news anchor, but it no longer bothers me so much. It’s ironic -- with nystagmus, the more one tries to steady the eyes, to shake the shaking, the more pronounced the oscillation becomes. The brain isn’t always able to compensate for reality, but it can certainly adjust to it.

Note: In this essay, I found a great deal of useful information in Life: the Science of Biology, by William Purves, et al., Sinauer Associates, 2001; the website of the Royal National Institute of the Blind (http://www.rnib.org.uk/); Eggert, Straube, and Schroeder’s “Visually induced motion perception and visual control of postural sway in congenital nystagmus” in Behavioural Brain Research, 1997, 161-168; Applied Vision Research Unit at the Institute of Behavioural Sciences, University of Derby (http://ibs.derby.ac.uk/gallery/types.shtml); W. Niemeyer and I. Starlinger’s article, “Do the blind hear better? Investigations on auditory processing in congenital or early acquired blindness. II. Central functions,” 1981, Macalester College Department of Psychology’s website, “Phatom Limbs” (http://www.macalester.edu/~psych/whathap/UBNRP/Phantom/homepage.html).

Many thanks to Mark Histed for his lucid explanations for and insightful remarks on the wondrous nature of the brain. .