Eyes Wide Shut
By Bobbi Falde
I can see more with my eyes closed. No really, when I close my eyes, I have a better sense of what is going on around me. This sounds bizarre if you can see with both of your eyes, but that is not the case for me. I have left homonymous hemianopsia. That is the really complicated way of saying I can only see with roughly half of my visual field (Cleveland Clinic, 2015). When I am somewhere that I need to see something or remember where I have placed an item, I close my eyes and allow my brain to tell me what the entire room looks like. Based on the looks of people who have caught me looking for something with my eyes shut, I have come to realize what an anomaly this is.
It was an unusually warm day in January causing the snow to melt and water to cover the highway. As any winter-weather driver knows, this can be a recipe for disaster. The vehicle I was in hit a patch of black ice and physics got the best of me. After being bounced around the vehicle, I sustained a parietal and occipital lobe traumatic brain injury (TBI).
The visual acuity changes that occur with hemianopsia are typically experienced with acute onset, like what is described in the case study Homonymous Hemianopia in a Young Adult: A Case Study written by K. Daily and Dr. Leonid Skorin (2016). The brain damage I sustained did not present itself until sometime later. Not because the injury hadn’t already occurred, but because I was not entirely aware that it was there. For several days, weeks even, I thought that I had a piece of my dark hair falling into my face. I would repeatedly push my dark hair behind my ears thinking that it was the culprit for the black blur blocking what I was looking at.
Little by little, more obvious signs began to arise. I would be completely taken aback when someone would “just appear” to my left even though they had been standing there for some time. I was beginning to get this awkward sense that I was not reading the whole story on the pages of books and articles. But the worst sign was the number of bruises to the left side of my body which was strange even for how clumsy I was.
Then it hit me. While I was walking through a door threshold, I almost knocked myself out with the amount of force I hit the left side with. It was as if the wall jumped out in front of me. I knew the threshold was there when I was walking up to it, but once it was within the outer 50 percent of my visual field it simply disappeared from sight.
With the help of my neurocognitive psychologist, on my TBI team, I learned humans see with their brains, not with their eyes, and this was the reason for the visual changes I was experiencing. He further explained to me that the problem was not in my eyeball, but in the interpretation and transmission of information coming into the right side of my visual cortex. Because of the way that our short-term and long-term memory work, I was able to store the incoming information into a visual image in my head that I could see when I close my eyes. When I focused on the “image” my brain had created for me, I could then see what I could not when my eyes are open. My eyes were consuming the information, my brain was just not interpreting it properly (Cleveland Clinic, 2015; National Eye Institute, 2019; Zhang et al.,2006).
Seeing with Our Brains
Essentially, our eyes are only good for perceiving information. It is our brains that deserve the credit for what we are “seeing” (National Eye Institute, 2019). While walking down the street, taking in everything around us, our eyes are collecting data that amounts to lines, basic shapes, and light. The photoreceptors, also known as the special cells in our eyes commonly referred to as rods and cones, collect information and translate it into a language that our brains can understand (American Academy of Ophthalmology, 2017). The retina then sends it down a pathway, called the optic nerve then on to our occipital lobe. It is here when the brain goes to work making those signals into the picture that we see. Depending on the side of the brain that has sustained injury, the opposite side of the visual field will be disrupted. For instance, I have a right sided brain injury, therefore I have left-sided vision disruption.
The leading cause of homonymous hemianopsia, according to the Cleveland Clinic, is an obstructive stroke (2015). However, injury to the visual cortex in the brain can potentially lead to similar visual disruption. The promising news is that many people experience some degree of recovery with this condition. The unfortunate news is the amount of visual recovery is completely dependent on the extent of the brain damage (Zhang et al., 2006). A skill many people develop in order to manage visual field loss is learning to turn their head in order to scan the entire room they are in. This clever adaptation allows them to “see” the entire room. Learning these strategies, and developing habitual patterns from them, is currently the leading treatment for this type of vision loss (Zhang et al., 2006).
Over the last four years I have recovered some of my visual field. I am able to drive a car, read books and avoid running into walls! This is considered significant progress for this type of injury and I credit my brain injury team, their expertise and quick treatment. I learned ways to compensate for my vision loss, and I lead a seemingly normal life. I may always have to explain what I am doing when I am caught scanning a room with my eyes shut, but it is an opportunity that I am grateful to my team for.
References
American Academy of Ophthalmology. (2017, September 28). Photoreceptors. https://www.aao.org/eye-health/anatomy/photoreceptors
Cleveland Clinic. (2015, April 17). Homonymous hemianopsia. https://my.clevelandclinic.org/health/diseases/15766-homonymous-hemianopsia-
Daily, K. & Skorin, L. (2016). Homonymous hemianopia in a young adult: A case report. Clinical and Refractive Optometry, 27(2), 68-73. https://www.researchgate.net/publication/324216533
National Eye Institute. (2019, July 16). How the eyes work. https://www.nei.nih.gov/learn-about-eye-health/healthy-vision/how-eyes-work
Zhang, X., Kedar, S., Lynn, M. J., Newman, N. J., & Biousse, V. (2006). Natural history of homonymous hemianopia. Neurology, 66(6), 901-905. https://doi.org/10.1212/01.wnl.0000203338.54323.22