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The human eye can function from very dark to very bright levels of light; its sensing capabilities reach across nine orders of magnitude. This means that the brightest and the darkest light signal that the eye can sense are a factor of roughly 1,000,000,000 apart. However, in any given moment of time, the eye can only sense a contrast ratio of ...
An important risk factor is increased intraocular pressure (pressure within the eye) either through increased production or decreased outflow of aqueous humour. [8] Increased resistance to outflow of aqueous humour may occur due to an abnormal trabecular meshwork or due to obliteration of the meshwork resulting from injury or disease of the iris.
[9] [10] He was the first person to explain that vision occurs when light bounces on an object and then is directed to one's eyes. [11] Leonardo da Vinci (1452–1519) is believed to be the first to recognize the special optical qualities of the eye. He wrote "The function of the human eye ... was described by a large number of authors in a ...
The human eye can detect a luminance from 10 −6 cd/m 2, or one millionth (0.000001) of a candela per square meter to 10 8 cd/m 2 or one hundred million (100,000,000) candelas per square meter. [ 19 ] [ 20 ] [ 21 ] (that is it has a range of 10 14 , or one hundred trillion 100,000,000,000,000, about 46.5 f-stops).
The cooperative eye hypothesis is not the only one that has been proposed to explain the appearance of the human eye. Other hypotheses include the proposal that white sclerae are a sign of good health, useful in mate selection, or that eye visibility promotes altruistic behaviour by letting people know they are being watched. A study by the Max ...
The human eye, showing the iris and pupil. In 1802, philosopher William Paley called it a miracle of "design."In 1859, Charles Darwin himself wrote in his Origin of Species, that the evolution of the eye by natural selection seemed at first glance "absurd in the highest possible degree". [3]
[2] [3] It has been established that the maximum spectral sensitivity of the human eye under daylight conditions is at a wavelength of 555 nm, while at night the peak shifts to 507 nm. [ 4 ] In photography , film and sensors are often described in terms of their spectral sensitivity, to supplement their characteristic curves that describe their ...
Accommodation is the process by which the vertebrate eye changes optical power to maintain a clear image or focus on an object as its distance varies. In this, distances vary for individuals from the far point—the maximum distance from the eye for which a clear image of an object can be seen, to the near point—the minimum distance for a ...