Ads
related to: vision factors for the eyes of lightconsumereview.org has been visited by 100K+ users in the past month
restorevisionclinic.com has been visited by 100K+ users in the past month
LensCrafters.com has been visited by 10K+ users in the past month
Search results
Results from the WOW.Com Content Network
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 ...
A reference value above which visual acuity is considered normal is called 6/6 vision, the USC equivalent of which is 20/20 vision: At 6 metres or 20 feet, a human eye with that performance is able to separate contours that are approximately 1.75 mm apart. [9] Vision of 6/12 corresponds to lower performance, while vision of 6/3 to better ...
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth. The human eye can distinguish about 10 million colors. [3]
[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 size of the pupil, which controls the amount of light entering the eye, is adjusted by the iris' dilator and sphincter muscles. Light energy enters the eye through the cornea, through the pupil and then through the lens. The lens shape is changed for near focus (accommodation) and is controlled by the ciliary muscle.
Vision is often one of the first senses affected by aging. A number of changes occur with aging: Over time, the lens becomes yellowed and may eventually become brown, a condition known as brunescence or brunescent cataract. Although many factors contribute to yellowing, lifetime exposure to ultraviolet light and aging are two main causes.
There are two luminous efficiency functions in common use. For everyday light levels, the photopic luminosity function best approximates the response of the human eye. For low light levels, the response of the human eye changes, and the scotopic curve applies. The photopic curve is the CIE standard curve used in the CIE 1931 color space.
The range is defined psychometrically by the luminous efficiency function, which accounts for all of these factors. In humans, there is a separate function for each of two visual systems, one for photopic vision, used in daylight, which is mediated by cone cells, and one for scotopic vision, used in dim light, which is mediated by rod cells ...
Ads
related to: vision factors for the eyes of lightconsumereview.org has been visited by 100K+ users in the past month
restorevisionclinic.com has been visited by 100K+ users in the past month
LensCrafters.com has been visited by 10K+ users in the past month