The blue field entoptic phenomenon or Scheerer phenomenon (after the German eye doctor Richard Scheerer, who first drew clinical attention in 1924) was the appearance of small bright dots (nicknamed < b> blue-sky sprites ) move quickly along dotted lines in the visual field, especially when seeing a bright blue light like the sky. The dots are short-lived, visible for a second or less, and travel a short distance along a random-looking, curved road. Some of them follow the same path as the predecessors. The points can extend along the way like small worms. Point velocity varies in sync with the pulses; they quickly accelerate on every beat of the heart. The dots appear in the field of view of the center, within 15 degrees of the fixation point. The left and right eyes see different points; someone who sees with both eyes sees a mixture.
Most people can see this phenomenon in the sky, though somewhat weak, and many people do not realize it until asked to pay attention. The dots are striking against the monochromatic blue background (~ 430 m) instead of the sky.
Video Blue field entoptic phenomenon
Description
The dots are white blood cells that move in the capillaries in front of the retina of the eye. Blue light (optimal wavelength: 430 nm) is absorbed by red blood cells that fill capillaries. The eye and brain "edit" the line of the capillary shadow, in part with the dark adaptation of the photoreceptor located beneath the capillary. White blood cells, which are much rarer than red blood cells and do not absorb blue light, create a gap in the blood column, and this gap appears as a bright spot. The gap lengthens because the white blood cells of the ball are too wide for the capillaries. Red blood cells accumulate behind white blood cells, appearing like a dark tail. The behavior of blood cells in retinal capillaries has been directly observed in human subjects by adaptive optics of laser ophthalmoscopy scanning, a real time imaging technique for examining retinal blood flow. The dots will not appear in the center of the visual field, as there are no blood vessels in the aval foveal zone.
Maps Blue field entoptic phenomenon
Blue field entoptoscopy
In a technique known as blue field entoptoscopy , the effect is used to estimate blood flow in retinal capillaries. The patient alternately shows blue light and computer-generated images from moving points; by adjusting the speed and density of these points, the patient tries to match the computer-generated image with perceived entoptic spots.
Differences from other entoptic phenomena
The Scheerer phenomenon can be easily distinguished from floaters ( muscae volitantes ). The Scheerer phenomenon consists of cells of the same diameter and visual acuity, from simple point or worm forms, brighter than the background. If the eye stops moving, the dots continue to shoot. If the eye moves, the dots follow immediately, as they are contained in the retina. In contrast, floaters are spots or threads with variable diameters and variable visual acuity, some complex shapes, darker than backgrounds. If the eyes stop moving, floaters become calm. If the eyes move, floaters follow sluggishly, as they are contained in vitreous humor that is subject to inertia.
The Scheerer phenomenon can be distinguished from the visual snow as it only appears when it sees a bright light, while visual snow is always present in all light conditions including dark.
See also
- Enoptic phenomena
- Floater
References
External links
- A video that describes the history and science of blue entoptic field phenomena and viewing techniques
Source of the article : Wikipedia
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