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The top and bottom images produce a dent or projection depending on whether viewed with cross- () or wall- () eyed vergence. An autostereogram is a two-dimensional (2D) image that can create the optical illusion of a three-dimensional (3D) scene. Autostereograms use only one image to accomplish the effect while normal stereograms require two.
Stereoscopy is the production of the illusion of depth in a photograph, movie, or other two-dimensional image by the presentation of a slightly different image to each eye, which adds the first of these cues ( stereopsis ). The two images are then combined in the brain to give the perception of depth.
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.
When both eyes are properly aligned and aimed at the same target, the visual portion of the brain fuses the two forms from the two eyes into a single image. When one eye turns inward, outward, upward, or downward, two different pictures are sent to the brain. Thus, the brain can no longer fuse the two images coming from the two eyes.
In neuroanatomy, the optic chiasm, or optic chiasma ( / ɒptɪk kaɪæzəm /; from Greek χίασμα 'crossing', from Ancient Greek χιάζω 'to mark with an X '), is the part of the brain where the optic nerves cross. It is located at the bottom of the brain immediately inferior to the hypothalamus. [1] The optic chiasm is found in all ...
Normal fundus photographs of the right eye (left image) and left eye (right image), seen from front so that left in each image is to the person's right. Each fundus has no sign of disease or pathology. The gaze is into the camera, so in each picture the macula is in the center of the image, and the optic disk is located towards the nose. Both ...
v. t. e. In neuroanatomy, the optic nerve, also known as the second cranial nerve, cranial nerve II, or simply CN II, is a paired cranial nerve that transmits visual information from the retina to the brain. In humans, the optic nerve is derived from optic stalks during the seventh week of development and is composed of retinal ganglion cell ...
Scintillating scotoma is a common visual aura that was first described by 19th-century physician Hubert Airy (1838–1903). Originating from the brain, it may precede a migraine headache, but can also occur acephalgically (without headache), also known as visual migraine or migraine aura. [ 4]