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At this distance, the symbols on the line representing "normal" acuity subtend an angle of five minutes of arc, and the thickness of the lines and of the spaces between the lines subtends one minute of arc. This line, designated 6/6 (or 20/20), is the smallest line that a person with normal acuity can read at a distance of 6 metres.
An example of the Landolt C eye chart (also known as the Japanese eye chart.). Numerous types of eye charts exist and are used in various situations. For example, the Snellen chart is designed for use at 6 meters or 20 feet, and is thus appropriate for testing distance vision, while the ETDRS chart is designed for use at 4 meters. [16]
English: Diagram of a human eye (horizontal section section of the right eye) Català: Diagrama de l'ull humà (secció horitzontal de l'ull dret) Español: Diagrama del ojo humano (sección horizontal del ojo derecho)
The Jaeger chart is an eye chart used in testing near visual acuity.It is a card on which paragraphs of text are printed, with the text sizes increasing from 0.37 mm to 2.5 mm. [1] This card is to be held by a patient at a fixed distance from the eye dependent on the J size being read.
The diagram on the right shows an observer's eye looking at a frontal extent (the vertical arrow) that has a linear size , located in the distance from point . For present purposes, point O {\displaystyle O} can represent the eye's nodal points at about the center of the lens, and also represent the center of the eye's entrance pupil that is ...
Spectral sensitivity is the relative efficiency of detection, of light or other signal, as a function of the frequency or wavelength of the signal. In visual neuroscience , spectral sensitivity is used to describe the different characteristics of the photopigments in the rod cells and cone cells in the retina of the eye .
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.
Schematic diagram of the human eye. It shows a horizontal section through the right eye. The eye is made up of three coats, or layers, enclosing various anatomical structures. The outermost layer, known as the fibrous tunic, is composed of the cornea and sclera, which provide shape to the eye and support the deeper structures.