From “Floaters” to “Visual Snow,” Do You Know the Causes Behind These Common Phenomena?
You may have noticed black specks floating in your vision (commonly referred to as “floatersâ€) when looking at a white wall or gazing up at the blue sky, and wondered why this happens. What exactly are they, and should you be concerned?
In reality, there are many visual phenomena that you may have experienced without even noticing. Below is a compilation of these phenomena along with explanations for them.
1. “Floaters”
What are these black threads floating in the sky?
These black specks that drift in front of your eyes are usually protein strands, such as collagen fibers, or occasionally tiny cells like photoreceptor cells that escape from the back of the eyeball. Collagen fibers are the primary cause of this phenomenon and they often clump together, forming a dark strand that you observe in your vision.
Most people experience this phenomenon, but some individuals tend to see “floaters” more frequently than others. Those who are nearsighted often experience more “floaters” because the horizontal axis of their eyeball (the distance from the lens to the retina) is usually longer than that of normal-sighted or farsighted individuals, causing the eye muscles to stretch, making it easier for protein strands or cells to escape.
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They can be protein strands or photoreceptor cells.
Additionally, as we age, we tend to notice more black specks because the substances in the vitreous humor change. In older adults, the vitreous humor often decreases and shrinks, pulling on the cells in the retina, making them more likely to see “floaters.”
Typically, we cannot make this phenomenon disappear because once they escape, the cells and protein strands will “float” indefinitely. Occasionally, some cells may be sucked back in. Some people even believe that specific eye movement exercises may help push these “obstructive” objects out of sight.
However, if you truly do not want to see “floaters†anymore, there are two surgical methods: retinal detachment surgery and floaters removal surgery that can address this issue.
2. Flickering White Spots
“Blue Entoptic Phenomenon” refers to the phenomenon where you see tiny white specks floating in your vision. They move very quickly and disappear just as fast.
White blood cells are the essence of these flickering white spots.
Essentially, red blood cells that dominate the interior of capillaries absorb light differently than white blood cells. The brain can accurately detect the colors that red blood cells perceive, thus for the brain, red blood cells blend into the scenery perceived by the eye.
Have you ever experienced this?
However, with white blood cells, due to their different sizes and lower prevalence, the brain perceives them as white spots and can thus see them. Occasionally, the white spots may have a black outline; this black outline is actually the gap created by the white blood cells as they rush through the blood flow in capillaries.
Since white blood cells are more transparent to blue light than red blood cells, we see a bright speck moving along the capillary. Under ideal observational conditions, you might even see a dark tail behind the white speck, which is the red blood cells piling up behind the white blood cells.
3. Visual Snow
When you close your eyes, do you notice these noise-like patterns similar to those of a TV screen?
The phenomenon of “visual snow” occurs when you see part or all of your vision covered by grainy particles or noise.
You may easily notice “visual snow” when you close your eyes or when looking in the dark. Almost everyone experiences this phenomenon but to varying degrees. For some individuals, this condition is severe enough to become a disorder that significantly disrupts their vision and overall health.
There is no precise explanation for the cause of this phenomenon. It may be the result of distorted perception of light stimuli occurring when the sensory cells become overly sensitive or when they send incorrect signals despite not receiving any light stimuli.
The vision of someone with “visual snow” is more limited than that of a normal person.
4. Eye Flashes
Eye flashes are the phenomenon of seeing bursts of light in your eyes without any light stimuli entering the eyes. You may experience this phenomenon when rubbing your closed eyes, sneezing or coughing too hard, experiencing a head trauma, or even when having low blood pressure. They are usually colorful, shapeless flashes of light that appear very quickly, a phenomenon described since ancient times by the Greeks.
A common case of “eye flashes” occurs when we rub our eyes or when we experience a head impact.
The reason for this phenomenon is due to external forces acting on the eyes that serve as stimulating signals to the retinal cells, causing them to react and create “eye flashes.” Additionally, “false” stimuli may arise from metabolic disturbances (lack of oxygen or glucose), which also causes neurons in the visual cortex to react.
Another case of “eye flashes” is when you focus on a light source for too long and then suddenly close your eyes or shift your gaze to a darker area; you may see a faint light trail lingering for a moment before fading away.
The explanation for this case is that the eyes continue to burn energy and release electrical signals even when at rest. When these electrical signals accumulate in large amounts, they are sufficient to stimulate the visual cells and create strange light streaks characteristic of “eye flashes.”
While everyone experiences this phenomenon, the amount and type vary widely. In the case of floaters, we often ignore them because the brain has learned to disregard them. However, an unusual increase in number or size that affects vision may be a sign of a serious condition requiring immediate medical attention.
