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Blue field entoptic phenomenon or Scheerer's phenomenon Blue field entoptic phenomenon or Scheerer's phenomenon
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Blue field entoptic phenomenon or Scheerer's phenomenon

The blue field entoptic phenomenon or Scheerer's phenomenon (not illustrated) can be seen best by looking at a sunny sky (see here). According to SopuliSusie (subject #405), "I always wondered about squiggly lines on blue skies, but I saw those since I was a kid, and so did all the other kids in the school yard, so I never worried."

Darting specks of light in my vision - know what they are?

"I've looked on sites the internet, but haven't been able to find out about these little darting specks of light that I see when I look up towards the sky. They don't appear to be in the sky, but are more like somehow produced in the actual eye, as I believe they move with the movement of my eyes. They're not 'floaters', as they look very different to them (much brighter, for starters). I've never noticed them when I've been indoors, so I think that bright natural light is a factor.

Yep, I'm fairly sure they only happen when I'm outdoors. I've only seem them in the daytime, and I think I can see them when it's cloudy, but I usually notice them more when it's sunny. I can't see them anymore when I close my eyes.

One thing I forgot to mention is that I have to let my eyes go out of focus to see them, and it's not just something that happens randomly, as I can actually see them at will, by doing this.

I have been seeing these things for as long as I remember and have never had anything medically wrong with my eyes (short-sightedness aside).

I'm not actually concerned that I might have anything wrong with my eyes, more curious as to what these things are, really. But I'll certainly take you're advice and ask about them next time I have an eye check. Why I haven't thought of that before is beyond me!"

(Gary Leo, Science Forums, The Original - Medical Sciences - Anatomy, Physiology and Neuroscience - Darting specks of light in my vision - know what they are?, January 30, 2005)

The blue field entoptic phenomenon or Scheerer's phenomenon (Scheerer, 1924) is the appearance of tiny bright dots moving quickly along squiggly lines in the visual field, especially when looking into blue light (such as the sky). This is a normal effect that can be perceived by almost everybody (Ford, 1967). The dots are due to the white blood cells that move in the capillaries in front of the retina of the eye, near the macula (Sinclair et al., 1989). Blue light (optimal wavelength: 430 nm) is well absorbed by the red blood cells that fill the capillaries. The brain "edits out" the dark lines that would result from this absorption. The white blood cells, which are much rarer than the red ones and do not absorb the blue light well, create gaps in the blood column, and these gaps appear as bright dots.

Blue Field Simulation/Entoptoscopy. © 2007 Uppsala University, Department of Ophthalmology (see here)

In a technique known as blue field entoptoscopy, the effect is used to measure the blood flow in the retinal capillaries (Abraham, 1983). The patient is alternatingly shown blue light and a computer generated picture of moving dots; by adjusting the speed and density of these dots, the patient tries to match the computer generated picture as best as possible to the perceived entoptic dots. This then allows calculation of the blood flow in the capillaries. This test is important in diseases such as diabetes mellitus which can cause retinopathy (Mittl et al., 1990).

The blue field entoptic phenomenon or Scheerer's phenomenon has also been used as a source of artistic inspiration. The singer/songwriter Juliana Hatfield alludes to the phenomenon in her song "I See You" (video available here) which includes the line, "What are all those dizzy circles in the corner of my eye? / They laugh and float away as I look into the sky."

In the absence of a physiological explanation, experients of the blue field entoptic phenomenon may invest Scheerer's phenomenon with a spiritual meaning, considering it as a vision of some sort of cosmic energy. In the 1920s, theosophists maintained that the moving spots seen in the phenomenon were "vitality globules" related to the concept of prana in yoga (Zusne and Jones, 1989).

I have sparkle vision - Is That Normal?

"Now that I'm living in a house and have a front porch again, I spend a lot more time just sitting outside staring at the sky, watching clouds and birds (Big Sky country is conducive to that). Anyway, I'm seeing the sparkles again. I used to see them all the time, but that was back when I was a whimisical, spaced-out art school student who often took to cloud-gazing for long periods of time.

This sparkle vision is probably a normal, common thing; some kind of natural, visual phenomena that occurs when you stare at bright backgrounds, such as the sky in daylight. But I've never heard anyone mention it. Then again, I’ve never mentioned it. It’s not one of those things that comes up in conversation, I guess.

What it looks like is a million tiny fireflies flickering in and out of sight, everywhere I look (everywhere with a light enough background to see them against). I used to romanticize it, imagining I was seeing through the surface into the aliveness of everything, seeing the energy itself which forms the universe.


Meanwhile I’ll just imagine that what I’m seeing is cosmic energy particles, like the 'Dust' in His Dark Materials, and it’s because I have super cosmic radio eyes."

(Brooke, Supernatural things - I have sparkle vision. Is That Normal?, April 7, 2007)

Anonymous, Visual snow/static, undated. © 2006 Anonymous (lost webpage)

Scheerer's phenomenon must not be confused with visual snow. The 2 phenomena can be distinguished from each other by a variety of phenomenological and clinical features as summarized in the table below. Scheerer's phenomenon is an entoptic phenomenon present in most healthy subjects, whereas visual snow is a transitory or persisting visual symptom where people see snow or television-like static in parts or the whole of their visual fields. According to the notion of hallucinatory form constants by Klüver (1942) and Siegel and Jarvik (1975), it can be conceived as a variety of visual hallucinations of random form dimension (see here). Visual snow is a symptom of ophthalmologic, neurological or psychiatric disease (like all other forms of visual hallucinations, it is non-specific as regards etiology, i.e. the cause of illness). Persistent visual snow is most frequently a symptom of persistent aura without infarction or Hallucinogen Persisting Perception Disorder (HPPD).

Differential diagnosis between Scheerer's phenomenon and visual snow

Scheerer's phenomenon

Visual snow



white, black or coloured (see here)

Distribution in visual field

multiple, identical-looking bright dots that follow each other rapidly along the same path

visual snow or TV-like static most often randomly distributed in the entire visual field

Effect of lighting conditions

only present in daylight conditions (most intense with bright sunlight), not in darkness

present in all lighting conditions, often more intense in darkness

Effect of eye closure

phenomenon disappears

phenomenon persists

Functional impairment

no functional impairment

often functional impairment (e.g. reading difficulties, impaired night vision)

Psychological strain


mild to severe

Association with other symptoms


frequently associated with other perception disturbances (e.g. visual loss, increased afterimages, tinnitus)

Illustrations of "mouches volantes" (floaters) from users of the German floater forum (see here)

Scheerer's phenomenon also must be differentiated from floaters (French mouches volantes, Latin muscae volitantes). Scheerer's phenomenon is distinguished from floaters by the appearance of multiple, identical-looking bright dots that follow each other rapidly along the same path. Floaters are variable in appearance; although they sometimes are dots, they often have the appearance of threads or shreds of crumpled cellophane. Floaters remain almost stationary or drift slowly and do not follow well-defined paths. They are due to debris floating in the vitreous humor of the eye.

Sarah A [subject #432], The power of naming, 2007. © 2007 Sarah A (larger image see here) [more]

A physician's failure to discriminate Scheerer's phenomenon or floaters from visual snow may result in the false negative misdiagnosis of declaring the subject healthy or in false positive misdiagnoses of considering the subject as hypochondriac, devoting too much attention to assumed normal or harmless pathological entoptic phenomena, or as exaggerating or even making up the symptoms "all in your head" (i.e., conversion or somatoform disorder).

Doctor's advice to visual snow sufferer

"Most of the things you are describing [see here] are entopic phenomena, that is sensations that arise from inside the eye. The most common is the 'flying corpusule'... entopic phenomena are not due to disease, nor can they be treated, nor are all people aware of them. Biggest problem is when people start to 'tune in' (hyper-awareness) on them and cause themselves anxiety. In the absence of other symptoms, it is questionable whether it is worth the time and cost of a neurological consult which will probably include a MRI possibly an EEG. After you review the archives of MedHelp.org and review the extensive literature available on the web, you should feel better about your 'problem'. If new symptoms develop or you can't dial back the anxiety level you may need to procede with a neurology work-up."

(JCH, MedHelp Eye Care Forum - The Eye Care Forum - Low Vision - Blood cells in retina or visual snow?, May 23, 2007; additions in square brackets by Klaus Podoll)

For example, Yawningtiger's (subject's #276) neurologist told her "that what we are describing as visual snow is perfectly normal", i.e. physiological entoptic phenomena. Christian S (subject #300) was told by several of his doctors (including an ophthalmologist and a neurologist) that all of his visual symptoms were just in his imagination. Similarly, SopuliSusie (subject #405) was told by one of her neurologists that "the problem 'is all in my head'", to which she quick-wittedly replied: "yeah, because that's where my brain is." Another doctor misdiagnosed this "problem patient" with conversion disorder, suggesting a mysterious leap from the mind to the body (Deutsch, 1959) as cause of her persistent aura without infarction.

I don't buy the theory that everyone has VS but they just don't pay attention to it

"Sorry, but I've asked lots of people if they can see VS, I've shown them simulations on the websites, I've asked them to 'try' to see it... and they still do NOT see it. They CANNOT see it because it is not there for them.

I don't buy the theory that everyone has VS but they just don't pay attention to it.


(Wendi Triplet Mom [subject #147], Ezboard forum Visual snow or static - Discussion - my story, May 8, 2007)

Visual snow is perfectly normal

"I just wanted to say that I saw a neurologist at the National Hospital in London a couple of weeks ago. She was sure - as I have often thought - that what we are describing as visual snow is perfectly normal, i.e. it is not a persistent aura. It is heightened perception of what makes up our vision. As I have mentioned before, my boyfriend says he can be aware of visual snow if he thinks about it, and the way he describes it is exactly as I experience it (just that I see it pretty much all the time and perhaps more prominently). I have now mentioned it to another friend, who said the same, and that he knows of others who are also aware of it too, particularly in the dark.

I don't particularly want to proclaim on this myself, and say anything for certain, particularly as I spent years being aware of this and several other phenomena and worrying about them and then - hey bingo - I developed a far worse migraine-related problem (it seems), which would suggest that all this is related. But at the same time it does seem to make sense that visual snow is a 'normal', physical thing or process to see, given that the blue field entoptic phenomenon (the whooshing little sprites or sperm-like sparkles you can see against light or blue backgrounds) and floaters are also physical items/processes, and some of us are far more aware of than we would ideally be.

I'm not saying AT ALL that being aware of visual snow is comfortable or fun or anything like that, but I worry that classifying it as a persistent migraine aura could be misleading - particularly as people with no other migraine symptoms and who are not particularly worried about it can see it too..."

(yawningtiger [subject #276], Ezboard forum Visual snow or static – Discussion - I am new..I have had visual snow for 19 years..., February 18, 2007)

It's all in your head

"I got labeled a problem patient after one of the neurologists told me the problem 'is all in my head,' and then I said with considerable sarcasm, 'yeah, because that's where my brain is.' He didn't like that.

I bet conversion disorder has to be one of the common misdiagnoses. I got that one. After that, I declared that I must be stuck in some kind of Cartesian duality Hell. At least that doctor had a sense of humor."

(SopuliSusie [subject #405], Ezboard forum Visual snow or static - Discussion - Visual snow comic, September 11, 2007)


Abraham MN. Blue field entoptoscopy. Indian J Ophthalmol 1983; 31:108-111.
Deutsch F (ed). On the Mysterious Leap from the Mind to the Body: A workshop study on the theory of conversion. International Universities Press, New York, N.Y. 1959.
Ford BJ. Conclusion on the White Dots of Scheerer's Phenomenon. Intelligence 1967; 99: 1.
Klüver H. Mechanisms of hallucinations. In: McNemar Q, Merrill MA (eds) Studies in personality. Contributed in honor of Lewis M. Terman. McGraw-Hill, New York-London 1942, 175-207.
Mittl RN, Tiwari R, Wilkes E. Blue field entoptoscopy in diabetic retinopathy. Indian J Ophthalmol 1990; 38: 10-13.
Scheerer R. Die entoptische Sichtbarkeit der Blutbewegungen im Auge und ihre klinische Bedeutung. Klinisches Monatsblatt Augenheilkunde 1924; 73: 67-107.
Siegel RK, Jarvik M. Drug-induced hallucinations in animals and man. In: Siegel R, West L (eds) Hallucinations: Behavior, experience, and theory. John Wiley and Sons, New York, NY 1975, 81-161.
Sinclair SH, Azar-Cavanagh M, Soper KA, Tuma RF, Mayrovitz HN. Investigation of the source of the blue field entoptic phenomenon. Investigative Ophthalmology & Visual Science 1989; 30: 668-673. [PDF]
Zusne L, Jones WH. Anomalistic Psychology: A Study of Magical Thinking. Lawrence Erlbaum Associates, Mahwah, NJ 1989.

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