Even in complete darkness, when we close our eyes, we may see strange patterns, like an unfinished visual display.
Image Source: Wikimedia
Many people may wonder, what are these ripples exactly? Can blind people also see these ripples?
For those of us with normal vision, the appearance of various "images" when closing our eyes is known as "phosphene." This phenomenon is quite common and not limited to just seeing ripples.
When you see stars after standing up for a long time, flashes of light when rubbing your eyes, or afterimages when staring at something and then closing your eyes suddenly, these are all examples of phosphenes.
There are various explanations for phosphenes, with two main theories being most prominent:
One suggests that this phenomenon occurs when pressure on the eyes activates the retinal nerve cells; while the other proposes that cells in different parts of the visual system either induce or spontaneously generate biophotons, which our eyes perceive.
Our eyes function like cameras, continuously gathering light that is then projected onto the retina. The retina contains several types of light-sensitive cells that become activated by light, converting it into electrical signals.
Subsequently, these electrical signals travel from the retina through the optic nerve to the brain, where they are interpreted, resulting in the images we perceive.
The first explanation of light phosphenes suggests that there is no actual light present; rather, it is a result of our photoreceptor cells or neurons being activated erroneously, leading to the perception of light phosphenes.
The second explanation posits that even when we close our eyes, light still exists. This light originates from our own cells during metabolic processes or chemical reactions, releasing photons that fall within the visible light spectrum. These photons activate the photoreceptor cells, enabling them to convert and transmit signals as if we were seeing something normally.
The reason why we typically see ripples but sometimes flashes is because under normal circumstances, cells release very few photons. However, external stimuli such as rubbing our eyes can trigger cells to rapidly release more photons, resulting in flashes of light.
Image: Afterimage, staring at a car, can still see a blurry car with eyes closed
The afterimage we mentioned earlier, caused by staring at something for a long time, is explained as a form of "stare stress." It keeps the photoreceptor cells in a state of "overexposure," so even when the visual stimulus stops, they continue to rapidly release photons, creating a ghostly image of the object.
So, do blind people experience these light illusions?
In reality, there is a common misconception about blind individuals, assuming they see absolutely nothing. However, the truth is that complete "light-insensitive" blindness is extremely rare.
For most blind people, they can perceive light, and some are very sensitive to light. This is why many blind people need to cover their eyes with black fabric or wear sunglasses.
For these blind individuals, at least some of their light-sensitive cells are still functioning normally, and their optic nerve cells are also fine. So, regardless of the cause of light hallucinations, they will experience such symptoms.
However, for those who are truly completely light-insensitive, can they still experience light hallucinations?
Most people subconsciously may think that completely blind individuals should see total darkness. However, with the sharing on the internet, many have heard that these blind people see a void instead of darkness.
Some even describe what this "void" feels like. It's like when you close one eye while keeping the other open.
I have read many self-descriptions from completely blind individuals, and indeed, some use "void" to describe what they "see" after losing their sight. But not everyone describes it this way; in fact, almost every blind person's visual experience is unique.
Damon Rose, a journalist from a well-known media outlet, is one of the few truly light-insensitive individuals. He often gives interviews to various media and shares what he can "see" with his eyes. We can find many of his related shares online.
Damon Rose lost his vision completely in childhood due to a mistaken surgery. He says he sees "light."
"A lot of light, bright, colorful, constantly changing, often distracting light." These are his exact words.
This is roughly what Damian Ross might have seen, image source: THINKSTOCK
Additionally, he described the scene as follows: a dark brown background with bright turquoise and green glowing parts in the front and middle, then shifting... the rest of the field of view is filled with flattened geometric shapes, curves, and clouds.
He mentioned that no matter what method you use, these images and "light" never disappear and are constantly changing. When he had just gone blind, he even thought this was the real light, a sign that his vision was about to improve.
Damian Ross's situation may not be visual hallucinations, and he doesn't experience significant visual hallucinations like we do by applying pressure to the eyes. He refers to his condition as "visual tinnitus."
Perhaps these phenomena are just his imagination. His photoreceptor and nerve cells may have completely lost their function.
However, Damian Ross cannot represent all completely blind individuals. He is a post-blindness individual, and some post-blind individuals do experience visual hallucinations.
The two mainstream explanations for visual hallucinations actually imply that our visual nerves can function, whether they are activated incorrectly or correctly, they can be activated.
Some completely blind individuals may only have photoreceptor cells completely nonfunctional, but nerve cells can still work. These cells have lost their signal source, so if these visual nerve cells are activated under certain conditions, visual hallucinations may occur (the first explanation of visual hallucinations seems more reasonable).
It is for this reason that scientists are actively working to restore partial vision to completely blind individuals who can experience visual hallucinations. Scientists capture images through devices, convert them into electrical signals, and then transmit them to nerve cells.
In simple terms, these devices replace the function of the eye's original photoreceptor cells. Existing technology can already allow a completely blind person to see the outlines of objects by wearing such a device.
On the other hand, some completely blind individuals are congenital, meaning they have never seen anything since birth.
There are significant differences between congenitally blind individuals and post-blind individuals. Some of them may also experience visual hallucinations because as long as their nerve cells can be activated normally, visual hallucinations can occur.
However, congenitally blind individuals cannot describe such scenes. They cannot understand vision and find it challenging to comprehend the visual sensations we describe to them.
In their eyes, it's not emptiness or darkness; it's simply a lack of any special perception. They use other senses to explore the world instead of vision.
