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Floaters or muscae volitantes are slowly drifting blobs of varying size, shape, and transparency, which are particularly noticeable when viewing a bright, featureless background (such as the sky) or a point source of diffuse light very close to the eye. They are shadow images of objects floating in liquid between the retina and the gel inside ...
The left and right eye see different, seemingly random, dot patterns; a person viewing through both eyes sees a combination of both left and right visual field disturbances. While seeing the phenomenon, lightly pressing inward on the sides of the eyeballs at the lateral canthus causes the movement to stop being fluid and the dots to move only ...
The third and fourth Purkinje images can be visible from within the eye itself. Light reflected away from the surfaces of the lens can in turn reflect back into the eye from the rear surface of the cornea. The first and fourth Purkinje images are used by some eye trackers, devices to measure the position of
Other medical conditions such as keratoconus (an eye disorder that results in extreme optic sensitivity to sunlight and bright lights), migraine which can be triggered by bright light, and porphyria cutanea tarda, which causes the skin to be overly sensitive to sunlight to the point of causing blisters, can result in heliophobia if the sufferer ...
The first patient in the U.S. was hospitalized with "severe" bird flu. Here's what you should know about symptoms, according to an infectious disease expert.
Impressions of several natural phenomena and the principles of some optical toys have been attributed to persistence of vision. In 1768, Patrick D'Arcy recognised the effect in "the luminous ring that we see by turning a torch quickly, the fire wheels in the fireworks, the flattened spindle shape we see in a vibrating cord, the continuous circle we see in a cogwheel that turns with speed". [8]
“When I was going on walks, I started feeling a burning sensation in my stomach,” she says. After the ultrasound showed a mass, Towle underwent an MRI. “(It) showed that it was cancerous ...
Astronauts who had recently returned from space missions to the Hubble Space Telescope, the International Space Station and Mir Space Station reported seeing the LF under different conditions. In order of decreasing frequency of reporting in a survey, they saw the LF in the dark, in dim light, in bright light and one reported that he saw them ...