blind spot

blind spot
1. Anat. a small area on the retina that is insensitive to light due to the interruption, where the optic nerve joins the retina, of the normal pattern of light-sensitive rods and cones. See diag. under eye.
2. an area or subject about which one is uninformed, prejudiced, or unappreciative: I confess that operettas are my blind spot.
3. Radio. an area in which signals are weak and their reception poor.
4. Also called dead spot. any part of an auditorium, arena, or the like, in which a person is unable to see or hear satisfactorily.
5. an area to the side and slightly behind a driver's field of vision that is not reflected in the vehicle's rearview mirror.
[1860-65]

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      small portion of the visual field of each eye (eye, human) that corresponds to the position of the optic disk (also known as the optic nerve head) within the retina. There are no photoreceptors (i.e., rods (rod) or cones (cone)) in the optic disk, and, therefore, there is no image detection in this area. The blind spot of the right eye is located to the right of the centre of vision and vice versa in the left eye. With both eyes open, the blind spots are not perceived because the visual fields of the two eyes overlap. Indeed, even with one eye closed, the blind spot can be difficult to detect subjectively because of the ability of the brain to “fill in” or ignore the missing portion of the image.

      The optic disk can be seen in the back of the eye with an ophthalmoscope. It is located on the nasal side of the macula lutea, is oval in shape, and is approximately 1.5 mm (0.06 inch) in diameter. It is also the entry point into the eye for major blood vessels (blood vessel) that serve the retina. The optic disk represents the beginning of the optic nerve (second cranial nerve) and the point where axons (axon) from over one million retinal ganglion cells coalesce. Clinical evaluation of the optic nerve head is critical in the diagnosis and monitoring of glaucoma and other optic neuropathies that may lead to vision loss.

Daniel M. Albert David M. Gamm
 

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Universalium. 2010.

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