What do blind people actually see? Most sighted people imagine that what the blind see is complete blackness. But it's not that black and white, so to speak.
There are different degrees and causes of blindness that affect what blind people can actually see.
Blind from birth
People who are blind from birth obviously have never had the ability to see. And it's not really our eyes that actually see information, but the brain that processes it.
So if the brain receives no signals from the eyes to process, a person can see nothing. It's not eternal darkness in front of them, like many of us assume. It's just complete nothingness.
To imagine what it's like, try closing one eye and looking around with only your open eye. The closed eye just sees nothing.
Another way to understand what it feels like is to answer one question. What can you see with your elbow? That's right, not blackness, just nothing.
People who lost their eyesight
Becoming totally blind, that is, losing light perception altogether, is extremely rare. It happens to those who have lost the connection between the eyes and the brain.
This can happen when the brain or optic nerve is damaged, or when the eyes are removed. People who lost their eyesight completely say it feels like being in a cave in total darkness.
Some people who were born sighted but lost the ability to see later in life may experience Charles Bonnet Syndrome, or CBS. It's kind of visual hallucination, where the person sees sparks in different shapes and colors, or flashes of bright light. It can be short bursts or last longer.
People who experience CBS aren't mentally ill or brain damaged, and they fully understand that what they see isn't real and is just a sort of a brain glitch.
When a lot of us think of blindness, we only imagine total blindness, but there is something called functional blindness as well. It means different things in different countries.
In Nigeria, normal vision is 6/6, and the higher the denominator, the worse the vision. A person with <3/60 vision is considered to have functional blindness, which means, with their better eye they cannot see at 3 metres what a person with normal eyesight can see at 60 metres.
There are different types of functional blindness, with varying levels of severity. A legally blind person can see people and large objects, but they're out of focus. They can perceive colors or even see things in focus but only at a certain distance, perhaps only as far as right in front of their face.
In some cases, everything they see is blurry and hazy. Some people experience a bunch of sparks of light constantly moving and changing colors. Legally blind people describe it as really quick, going from brown to turquoise with flecks of yellow or green in a matter of seconds.
Keeping light perception doesn't help blind people see clearly, but it does help them distinguish between light and dark, day and night. Some of them can also tell where the light's coming from.
People with tunnel vision look at the world kind of like through a narrow tube, hence the name. They might see things pretty clearly, but only within a field of vision less than 10 degrees. They don't see their peripherals at all.
This condition is often caused by optic nerve damage. Seeing nothingness or specks of light is what happens to blind people during the day. But what about at night, when it's time to go to bed and have dreams? Is it any different then? Do blind people see images in their dreams?
Again, it's different for people blind from birth and those who lost the ability to see later in life. People who have always been blind dream with their other senses. They can sense odors, sounds, flavors, and feel things by touch. They can feel happy, sad or scared, or whatever emotion comes to them. But images? Nope, they don't see things in their dreams.
A person who once could see and then lost their vision may see dreams like sighted people do, with bright vivid images. Legally blind people can also see images while they're sleeping. A person's health condition and personal eyesight history affects what and how well they can see in their dreams. A colorblind person, for example, won't get a new color range in his sleep.
Someone who's vision worsened might see things sharp and clear as they used to in the past or blurry like they do now. People who wear glasses or contacts can dream in or out of focus. And those who experienced Charles Bonnet syndrome during the day can also have it in their dreams. In that case, they'll see bright flashes of light even while sleeping.
Scientists at the University of Copenhagen delved even further to find out what the blind see in their dreams. It turns out that around 25% of their dreams are nightmares. They get them four times more often than sighted people. Using other senses.
Another popular question concerning people with impairment or loss of vision is if their other senses get stronger. Researchers believe it's true. Blind people remember how different objects smell and often use hearing and touch to find their way around. They discover the world using those senses and store the information they get this way for orientation.
Anyone who's felt their way around their house in pitch dark in search of a candle or flashlight during a power outage can understand this technique. Perceiving light non-visually. As we mentioned earlier, total loss of light perception is super rare, but it still happens. And it's possible that totally blind people have their own way of perceiving light.
In 1923, Harvard graduate student Clyde Keeler conducted some research on blind mice. Although their eyes lacked certain parts necessary for vision, they still followed day-night cycles. Their pupils even reacted to light. Scientists went back to non-visual light perception research 80 years later and found that both humans and mice have special photosensitive cells not on the retina, but on the nerves that send signals to the brain. These cells don't take part in the vision process, but they do help distinguish light from dark.
Conclusion
If you know anything else on this topic, share your knowledge in the comments below. And if this post helped you find out something new, share it to your loved ones and come back to Lafiyata as we'll share more curious health facts.
References
2. Ammons, C., Worchel, P., & Dallenbach, K. (1953). Facial vision: The perception of obstacles out-of-doors by blinded, blindfolded and deafened subjects. American Journal of Psychology, 66(4), 519–534.
3. Ashmead, D., Hill, E., & Talor, C. (1989). Obstacle perception by congenitally blind children. Perception & Psychophysics, 46(5), 425–433.
4. Cotzin, M., & Dallenbach, K. (1950). “Facial vision:” The role of pitch and loudness in the perception of obstacles by the blind. American Journal of Psychology, 63, 485–515.
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