Chez PLJ

Wherein Peter gets pretty in-depth into Jon’s ever more interesting visual perception.

We pop up to Waterloo more or less yearly in order that Jon get an eye examination from Dr. Rick Wiggins of the University of Waterloo Optometry Department. Dr. Wiggins is a specialist in Low Vision and Special Needs kids, so Jon is right up his alley, and we have yet to meet anyone as skilful as him. He has all sorts of strategies for dealing with vision and perceptual problems, and I’m sure that we’ve only seen a fraction of the tricks up his sleeve. We’re big fans.

Usually when we visit, Dr. Wiggins is flanked by a couple of students, who undertake the actual examination. An excellent instructor, he observes, advising and chatting where necessary, and holding back when the students are on the right course. He will occasionally do a quick repeat of a few particular exams through the course of the session, and end it with a quick series of checks of the patient himself, just to make sure everything looks copacetic. The exam in total takes around an hour.

He last saw us two and a half years ago, when they prescribed Jon glasses for nearsightedness (something he had predicted years before, given Jon’s genetic forebears—me and Laura), and then again six months later to make sure nothing had shifted (there had been a minor shift, but nothing that required a change in prescription).

This time around, there were no students, just the good doctor, Jon and me (Laura is on a short-term contract deadline). Dr. Wiggins brought Jon out of his shell immediately, assisted ably by the movie Cars, which Dr. Wiggins used in about half his tests that day. (As the kid watches the TV, he can observe how they use their glasses, and even use special equipment to see their eye lens as they watch. It’s fascinating to see such a skilled pro at work.) The exam seemed a bit more detailed than usual, and it, well, didn’t seem to stop. And about 95 minutes or so in, the good doctor finally confided his thoughts to me.

But first, a refresher

Part of Jon’s cerebral palsy damage has left him with Cortical Visual Impairment (CVI). This means damage to the brain in the area where your brain that interprets the data coming from your eyes into what you “see”. The upshot of this is that Jon didn’t have any decent vision before 18 months, whereas by then most humans have built up that section of the brain with what they need for interpreting vision for life. For kids with CVI, this means some permanent disadvantage. For although vision comprehension can improve, nothing can make up for that lost window of scheduled visual development time. (For those who can find it, there’s a wonderful Oliver Sacks essay about it called “To See of Not to See”.)

CVI can present in many ways, including uncoordinated eye movements, called nystagmus, where the eyes unpredicatably dart away from where the brain thinks they are looking. This, of course, screws up visual comprehension.

Another aspect affected is the co-ordination of 3D vision. In normal human development, binocular vision is co-ordinated at around a year. At that point, if the brain finds one eye to be weaker, it will skip 3D vision and assign the stronger eye a higher percentage of brain space: that eye becomes primary. Since early childhood, Jon has shown a “lazy eye”, but further observation showed that he was switching eyes from moment to moment. Which is to say, neither eye was so much lazy as independent, uncoordinated from each other.

CVI may also affect perception in different regions of Jon’s visual field, or different moments that he can perceive them. It’s been said that having CVI is like looking through a piece of moving Swiss cheese.

One important thing to note about all of this CVI stuff is that it is purely in the later processing of the image (the television control room, as it were): it has nothing to do with the eye hardware (the camera). Hence, through Jon’s early childhood, glasses could not help because the damage was in the brain, which had nothing to do with focusing. At nine and a half, Jon’s eyes had developed nearsightedness, which is something that glasses can do something about, so that’s when he got glasses.

Back the the Present

So what were these interesting findings?

The independent “lazy” eye: Jon is now favouring the left, but the right still gets some broadcast time. Still amazing. Is he using them for different elements of vision?

Jon’s nystagmus: Has changed. You can have left-or-right or up-or-down versions, and there’s also a rotational version, which is more complex and the hardest for the brain to compensate for (the others follow a more predictable pattern). Up until now, Jon’s eyes showed a rotational type nystagmus, but now it appears to have settled into a more horizontal pattern. This change is considered odd and interesting. Generally, the brain doesn’t remap a spurious sensory error to a different version of that error. Curiouser and curiouser.

Glasses and Focusing (wherein we leave Kansas): Jon’s glasses have been drooping a bit this past while. We had assumed that it was because he is growing out of them—well, he is—and maybe the prescription needed to be upped (especially since he still insisted that he needed them). Dr. Wiggins observed him, had him look at things, watched his eyes carefully, and observed his eye lenses in three separate independent tests, all very different. They all said the same thing.

Let’s put it this way, as described to me: Humans beings are generally born farsighted to a degree, and gradually over childhood their vision stabilizes around “normal”. Some eyes end the process a tad too early and stay somewhat farsighted, some go a little too far and stabilize in nearsightedness, like Laura and I and Jon (ahem). A nice sloping line on a graph. That basically goes flatline, or degrades gently, generally. A nice, serene line that doesn’t do crazy, wacky things like head back up to normality. Right?

Well, these tests have suggested Jon’s eyes have done exactly that in the past two years. In fact, the perturbation from his prescription noted at the second appointment two years was actually a slight improvement in his nearsightedness, which can now be seen as the beginning of the recovery to more-or-less normal uncorrected vision.

Dr. Wiggins had noticed right off the bat that Jon was intentionally looking over his lenses. He took his time methodically examining Jon because as he was confirming this, and he wanted to ensure that he could find no other medical issues, nor could he think of any negative medical implications to what he was describing. He confirmed it, and he couldn’t think of a downside. But it was throwing him for a loop, because human eyes do not usually recover to normal focusing like that. Also, this is not likely to have anything to do with brain development, because we’re talking about the lenses and focal length within Jon’s eyeballs.

We discussed the possibility of doing a fourth test, which would be the ol’ eye drops in the eye, paralysing the lens muscles and leaving the lens in its dormant state. I wasn’t against it, but knew it would take another hour of the doctor’s time. I did ask (with my twenty-year-old junior-researcher hat on) what a dissenting result in this test would mean to the overall results. Which is to say, if the result is the same, great, everything is confirmed; but if not, did it override the other results, or how do we interpret it? To which Dr. Wiggins replied, “If it is a minor deviation, I’d credit that to a reaction to the pharmaceutical. And if it’s a major deviation from the other results…I’d still say it was a negative reaction to the pharmaceutical.” In other words, if it didn’t support the other findings, it would be ignored. So we skipped the test this time. But next time, definitely.

We’re going to return in five months (we both agreed on six months, but then the good doctor cut that back by a month out of friendly impatience to do more tests 🙂 ). That gives Jon’s eyes 150 days to get back where they should be on the charts, or Dr. Wiggins gets to be first author on a research paper he doesn’t want to write. In the meantime, we have our homework: Jon can wear his glasses regularly or not, but we are to have them off him for some time to see how he adapts to seeing things ten or more feet away. Does he squint or tilt his head back? Or does he seem more comfortable? If he doesn’t want to part with his glasses, but is clearly more comfortable without them, we are even allowed to pop the lenses out!

To be continued in April!