Incredible! This is how the world looks like to the blind and colorblind...

Reviewers of this article:

Tao Ning, PhD, Associate Professor at National Institute

Chen Haixu, Deputy Director, Second Medical Center, PLA General Hospital, Master Supervisor

Our eyes help us understand the world, but what does the world look like to people with visual impairments?

There are many types of visual impairment. For example, some people are born with blindness, while others become blind due to accidents. Some patients are completely blind, while others are only partially blind. Today, let's take a look at the world through the eyes of 6 different types of visually impaired people.

Totally blind people do not recognize black

It was once believed that blind people see only darkness, but this is not true. For patients with congenital total blindness, they are born without vision. It is not that their eyes cannot see, but that their brains cannot process visual information. Since they have never seen black, how can they understand the concept of "black" that we are talking about?

Some patients with congenital total blindness complained that they are often asked whether it is pitch black in front of their eyes. They feel helpless: So what exactly is black?

What their eyes receive is "nothing", it is empty.

If you also want to simulate this feeling, you may want to try a method that is widely circulated on the Internet: you can try to close one eye and cover it with your hand, and only look at things with the other eye. At this time, what you observe with your closed eye is the legendary void, that is, nothing.

Even so, people who are born totally blind still dream.

Patients describe that in their dreams, no images or pictures appear, but other senses such as touch and smell can make up their dreams.

Hallucinations often occur after blindness

The phenomenon of total blindness caused by various accidents is relatively rare, but it still exists. Generally speaking, the patient is blind because the optic nerve in the brain is damaged or the eyeball is removed.

For such a group, they have seen what various things in the world look like, have pictures and concepts of many things, and they can also understand what black means.

After becoming blind, the world that was once visible to the naked eye suddenly becomes empty, with nothing left. According to patients with acquired total blindness, the pictures in front of their eyes are black, as if they are in a completely dark cave.

Therefore, according to scientists' investigations and statistics, such patients are particularly prone to nightmares, and physical and psychological trauma increases the frequency of nightmares.

One symptom that must be mentioned here is Charles Bonnet Syndrome (CBS), also known as visual release hallucinations. It refers to a complex visual hallucination symptom that occurs in patients with vision loss or visual field defects, mostly in elderly patients.

In other words, although they are pathologically unable to see anything, they often insist that they can sometimes see a flash of light, people, cars, buildings and other things around them.

Dr. Oliver Sacks of New York University Hospital explained that this phenomenon often occurs in patients who are completely blind or partially blind, and the flashing images are mostly projections of past memories.

A blind man with blurry vision

Not all blind people are completely blind. Some are partially blind. Rather than the word "blindness", it may be more accurate to describe them as "visual impairment".

The situations of people with visual impairments are also different. For example, a visually impaired person in the United States named Marc Muszynski sees a world full of light.

Marc has visual impairment due to a gene mutation. His ABCA4 gene mutated, causing him to gradually lose his photoreceptor cells after birth. He had normal vision when he was born, but he didn't find out that there was a problem with his vision until he took a vision test after going to kindergarten. He couldn't see the objects that the teacher asked him to identify. So he went to the hospital, and the doctor diagnosed him with a visual impairment caused by a gene mutation.

According to Marc, there was a blur in the middle of his visual image and he was unable to distinguish colors.

In addition, his eyes were particularly sensitive to light, so when he went out and walked in the sun during the day, the world was dazzling and particularly bright to him.

Every time he communicated with others, he could not see the other person's face clearly, and everything he saw was blurry. Everything in the world before his eyes was out of focus.

A blind person who can only perceive light

There is a group of visually impaired patients who can only feel the existence of light, which means that their eyes can sense whether the light is shining down, and some people can even distinguish the light source. Apart from light, everything else does not exist and is empty.

Some people see everything as round

In the eyes of patients with tubular vision disorder, what they can see is limited to objects within a certain range, and their field of vision is restricted. It feels like looking at everything through a tube. This disease is usually caused by damage to the optic nerve.

To make a simple simulation, we can roll a piece of paper into a cylinder, or directly put a tube in front of our eyes. At this time, our field of vision is relatively narrow, and we cannot see anything outside the cylinder. This condition is exactly the pain that patients have to endure on a daily basis.

What do traffic lights look like to color blind people?

Color blindness is one of the most common visual impairments. Many people do not realize that they have color blindness unless they go to the hospital because their color vision impairment is relatively mild.

Color blindness can be roughly divided into red-green color blindness, blue-yellow color blindness, and total color blindness. In the eyes of a person with normal color vision, a traffic light looks like this:

People with red color blindness cannot distinguish the color red, so there is no red in the traffic lights they see.

Deuteranopia cannot distinguish green, and the traffic lights in their eyes look like the following picture. From the perspective of ordinary people, the colors of the picture are somewhat similar to the traffic lights in the eyes of red blindness:

Blue-yellow color blindness is unable to distinguish between blue and yellow. In their eyes, traffic lights and blue sky are completely different. Blue and yellow are missing in their vision:

In the eyes of patients with total color blindness, everything is gray, with only light and dark differences. This condition is quite rare.

Let's compare a set of pictures. Vegetables and fruits look like this in the eyes of ordinary people:

In the eyes of people with red-green color blindness, red and green are missing:

For people with tritanopia, blue and yellow disappear, and red becomes more vivid:

Putting these four situations in the same frame, the visual impact is more obvious.

After watching these simulations of the perspectives of people with various visual impairments, I realized how deeply I had misunderstood the world they could "see"...

Source: Kuangwan Research Institute (ID: kuangwanplay)

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