Six years after a stroke punched a hole in my brain, I continue to improve. One area of damage was in the visual processing part of my brain, the left occipital cortex. Since then, I've had an annual check-up with my ophthalmologist, Dr Mercer, who first saw me after the stroke.
When I'd first turned up at her consultation room, still discovering the implications of a damaged brain, she asked, "Are you driving?"
"Yes," I said, surprised by the question.
"We'd better check you out then, to see if you're okay to do that."
Her assistant took me into a side room and sat me in front of a large metal box with two black eyepieces protruding from it. A contraption held my chin in place so that my head didn't move. I saw a large, illuminated circle filling my field of vision. She handed me an electronic button to click whenever I saw a flash of light within the circle. Over the course of a minute or so, pinpoint flashes of light appeared randomly in the circle; each time, I pressed the button. Sometimes there were large gaps between flashes and I wondered what this meant.
Afterwards, Dr Mercer checked my eyes and said they were fine. She printed off the results from the visual field test and clucked in recognition. Pointing with a pen she said, "You've lost a quarter of your visual field: right superior quadrantanopia." Sure enough, there was a chunk of darkness in the top right-hand quarter of my visual field.
This explained the smudginess I'd been noticing in my vision, as if a heavy rain cloud was hanging over me; something I hadn't given much thought to. So, from what Dr Mercer told me, my eyes were fine, and the optic nerves taking the visual sense data from my eyes to the brain were fine, but my brain (the occipital cortex) was not: it was unable to take in all the data as it had before.
The left side of the brain in most people manages the right side of their bodies; the damage to the left side of my brain was affecting the right side of my vision. If my brain had been taking a literal view of the world it should have looked to me like a pizza with a quarter slice taken out. Instead, my clever brain was inferring what it thought was missing, hence the smudgy black cloud.
Dr Mercer said I was okay to drive, as most of what I needed to see when driving was lower down in my visual field, but I needed to be mindful of the gap in my vision higher up. I live in the countryside where we have few traffic lights, so not being able to see up high isn't an issue. But on one occasion, I was driving in the city and ran through a red traffic light, almost swiping the car of an elderly driver who was legitimately turning across my line of travel. We pulled our cars over and I could see that the traffic lights had been too high in my visual field to see, when up close. I apologised to the driver and his shaken wife. That morning I'd felt fatigued after a day spent in the city and a poor night's sleep. This incident, and a few others, showed me that when I was mentally or physically fatigued, my vision deteriorated- fatigue blindness.
When Dr Mercer had first determined the extent of my visual field loss, I'd asked her if my full vision would ever return?
At the time, getting my vision back was the least of my concerns because the stroke had affected my auditory processing-a more disabling deficit-and I was dealing with other life crises (See my memoir: How I Rescued My Brain, Scribe). As a consequence, I've given the rehabilitation of my vision little attention. I caught up with Dr Mercer last week, now six years after the stroke. As usual, we both bent over the visual field printout, like two punters checking the field guide.
"You'll get your full vision back in no time," she'd said, as if it was the temporary loss of a possession.
"Is there anything I can do that would help?"
"Gentle exercise, like walking on the beach, taking it easy." She also suggested looking at absorbing visual images like Mandelbrot patterns.
After stepping outside Dr Mercer's office and blinking in the sunlight, I reflected on what she'd said. Yes, that's what I've done. I exercised, increasing the intensity and variety as I could, ate well and added supplements known to help brain function, meditated, slept, kept stimulating my visual cortex by being out and about, and most of all, had allowed time for my body's 'natural self-healing mechanism' to do its work. And hey, now I've got my eyesight back!
It was then that she said, "I'd call that normal vision."
"Why do you think it has come back?" I asked
"We are a natural self-healing mechanism. We'd all be dead by twenty if we were not self-healing. Our body returns to balance if we support it to do so, which you've done."