When looking at a clear sky or other clear and uniform surface, some see mysterious bright points or some translucent structures. A popular explanation is that they are our own blood cells. We decided to check if this is correct.
People describe mysterious points in different ways: some see bright “comets” with a dark tail, others notice figures that look like curved glass worms. Internet users call them flies/midges, dead pixels or swimmers and offer a wide variety of explanations - from lint and debris to bacteria or cholesterol. However, specialized ophthalmic sites, sites hospitals And Media they confidently talk about white blood cells or leukocytes, although on medical forums you can find statement and that these are red blood cells - erythrocytes. In some media, for example on the website BBC, it is argued that these can be both the cells of the body itself and external elements.
Leukocytes are white blood cells cells, which play a key role in the immune defense of the body, including the eyes. In the eye, leukocytes can be found in different structures and fluids. On the surface of the eye, in the mucous membrane of the conjunctiva, present a persistent small population of white blood cells, mainly T lymphocytes and macrophages, that provide local immune surveillance. Their amount in tear fluid may vary depending on the time of day and wakefulness status. At inflammatory In conditions such as uveitis (inflammation of the uvea), leukocytes intensively migrate into the uvea, including the iris and ciliary body. They can also penetrate into the anterior chamber of the eye, where, with severe inflammation, accumulations of white blood cells form - hypopyon. Leukocytes can also be present in the retina and vitreous body, especially in pathologies or injuries - here their presence is associated with the inflammatory process and the immune response to damage. The vessels that run through the eye also contain white blood cells.
These vessels are located in front of the visual cells, so, on the one hand, seeing your vessels is quite possible. However, it is important to understand that the picture from visual signals is formed not in the eye, but in the brain. The brain literally “filters out” unnecessary information - for example, about the presence of these vessels. On the other hand, blood cells are extremely small - the size of a white blood cell amounts to only 12–15 microns in diameter, it should be impossible to see them with the naked eye. However, the vessels still cast shadows and form angioscotomas - small areas of loss of the visual field in those places where large blood vessels pass. At the same time, the brain does not perceive these areas as blind spots, automatically completing the picture.
When the brain, for some reason, does not filter out unnecessary information, various entoptic phenomena arise - subjective visual sensations (for example, light or dark spots, lines, flashes) resulting from processes occurring inside the eye itself, and not due to external stimuli.
Bright moving dots, sometimes with a dark tail, that we see, especially when looking at a uniform surface - no matter how incredible it may sound, really our white blood cells that pass through the vessels of the eye. As mentioned above, leukocytes are white blood cells, so we see them as bright white dots. Leukocytes move through the vascular bed more slowly than red blood cells - erythrocytes. In turn, red blood cells carry hemoglobin, which absorbs light, so a dark tail can stretch behind the bright white point - a cluster of red blood cells that do not transmit light. These dots are not a pathology of vision, but a normal process, which even has a scientific name: the entoptic phenomenon of the blue field, or Shearer's phenomenon.
Ophthalmologists note that people usually see these luminous points in the central region of the field of view, and not in the side. At the same time, the very center remains “clean”, since there are no blood vessels there. Shearer phenomenon Maybe anyone can watch. True, most people usually do not concentrate on these luminous points and are convinced that they do not see their white blood cells until, for example, the doctor asks the patient to specifically track this phenomenon. Most prominent leukocytes will become provided that a person concentrates on them and a special length of light, namely blue light with a wavelength of about 430 nm.
Ophthalmologists use this phenomenon is used to assess the speed of blood flow in the vessels of the retina and diagnose eye pathologies. For example this method allows identify glaucoma at an early stage. Also a study of the entoptic phenomenon of the blue field Can use in assessing vision recovery after eye injury.
However, such tests require strictly defined lighting conditions and good concentration of the patient on his sensations. So far, the use of this phenomenon has not become widespread as a mass diagnostic method. But specialized organizations notethat this method can potentially be used for early diagnosis of diseases affecting macular function and microcirculation of the eye. It does not require special equipment, since self-diagnosis of patients at risk is sufficient.
But “glass worms” are not blood cells, and they arise for a different reason. To designate them even exists separate Latin name: muscae volitantes (literally - “floating flies”), but in Russian-language sources they are more often called flying. The state in which a person sees all these objects can be called myodesopsia.
On average, every fourth person aged 50 faces with such phenomena, and by the age of 80, 87% of people are already “acquainted” with floaters. However, younger people, including children and teenagers, may also see similar structures. First of all, these are those who suffer from myopia, overwork, or work at the computer for a long time. First of all, floaters arise due to changes in the vitreous body. Typically this jelly-like substance is homogeneous and therefore does not produce any distortion. However, with age or during certain periods of life (puberty, pregnancy), as well as due to a number of diseases (for example, diabetes mellitus), some of its fibers lose elasticity, curling and crumpling. When these lumps pass in front of the macula (the very center of the retina), their shadows form these very “glass worms” or “floaters”. That is, such structures are not individual cells, unlike leukocytes in the Shearer phenomenon, but microscopic fibers that would be impossible to see with the naked eye.
Reputable medical organizations (for example, clinics Mayo And Cleveland, American Academy of Ophthalmology) explain that the appearance of floaters is a normal physiological process of aging. At the same time, their sudden appearance, an increase in their number, a decrease in visual acuity, or pain in the eye may indicate the onset of retinal detachment - a condition that threatens vision loss and requires urgent medical attention.
In addition to these two entoptic phenomena, there are a number of other optical phenomena, also caused not by external visual stimuli, but by processes occurring in the eye. For example, when pressing on the eyeball, you may experience a sensation of a sharp flash of light due to mechanical irritation of the retinal structures. This is a mechanophosphene. Photopsia (flares) can be visible, for example, during eye movements against the background of optic nerve pathology. When looking at polarized light (a blue sky opposite the sun or any bright background), you can see Heidinger's brushes - a light yellow horizontal line or propeller-shaped figure.
Thus, strange bright spots, “comets” and “glass worms” are nothing more than movements or shadows cast by various structures within the eye itself. Bright dots are leukocytes, white blood cells, and dark ones are red blood cells that move along the vascular bed behind them. But the translucent complex patterns are no longer individual cells, but clusters of protein fibers that we see when they float inside the vitreous body in front of the retina.
Cover image: American Optometric Association
Read on the topic:
If you find a spelling or grammatical error, please let us know by highlighting the error text and clicking Ctrl+Enter.
