Search results
Results From The WOW.Com Content Network
This can be seen when the eyes are closed and looking at the back of the eyelids. In a bright room, a dark red can be seen, owing to a small amount of light penetrating the eyelids and taking on the color of the blood it has passed through. In a dark room, blackness can be seen or the object can be more colourful.
Another way in which the shadows of blood vessels may be seen is by holding a bright light against the eyelid at the corner of the eye. The light penetrates the eye and casts a shadow on the blood vessels as described previously. The light must be jiggled to defeat adaptation.
One example of a pressure phosphene is demonstrated by gently pressing the side of one's eye and observing a colored ring of light on the opposite side, as detailed by Isaac Newton. [ 7 ] [ 8 ] [ 9 ] Another common phosphene is "seeing stars" from a sneeze , laughter, a heavy and deep cough, blowing of the nose , a blow on the head or low blood ...
An animated sequence of simulated appearances of a red flower (of a zonal geranium) and background foliage under photopic, mesopic, and scotopic conditions. The Purkinje effect or Purkinje phenomenon (Czech: [ˈpurkɪɲɛ] ⓘ; sometimes called the Purkinje shift, often pronounced / p ər ˈ k ɪ n dʒ i /) [1] is the tendency for the peak luminance sensitivity of the eye to shift toward the ...
Rheum from a cat's eyes. Rheum (/ r uː m /; from Greek: ῥεῦμα rheuma 'a flowing, rheum') is a thin mucus naturally discharged from the eyes, nose, or mouth, often during sleep (contrast with mucopurulent discharge). [1] [2] [3] Rheum dries and gathers as a crust in the corners of the eyes or the mouth, on the eyelids, or under the nose. [3]
For example, the night sky looks darker than Eigengrau because of the contrast provided by the stars. Contrast threshold data, collected by Blackwell [5] and plotted by Crumey, shows Eigengrau occurring at adaptation luminances below approximately 10 − 5 cd m −2 (25.08 mag arcsec −2). [6] This is a limiting case of Ricco's law.
The tapetum lucidum, in animals that have it, can produce eyeshine, for example as seen in cat eyes at night. Red-eye effect, a reflection of red blood vessels, appears in the eyes of humans and other animals that have no tapetum lucidum, hence no eyeshine, and rarely in animals that have a tapetum lucidum. The red-eye effect is a photographic ...
Cyanopsia primarily affects the retina, the light-sensitive layer at the back of the eye, and sometimes the optic nerve, which transmits visual signals to the brain. The retina contains specialized cells called photoreceptors, which are responsible for detecting light and color. In cyanopsia, these photoreceptors, particularly the ones ...