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In humans, the pupil is circular, but its shape varies between species; some cats, reptiles, and foxes have vertical slit pupils, goats and sheep have horizontally oriented pupils, and some catfish have annular types. [3] In optical terms, the anatomical pupil is the eye's aperture and the iris is the aperture stop.
The pupil of the human eye can range in size from 2 mm to over 8 mm to adapt to the environment. 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.
This type of eye is common in mammals, including humans. The simplest eyes are pit eyes. They are eye-spots which may be set into a pit to reduce the angle of light that enters and affects the eye-spot, to allow the organism to deduce the angle of incoming light. [1] Eyes enable several photo response functions that are independent of vision.
Humans, other primates, and dogs have round (spherical) pupils, which are useful for general all-round vision. Cats, snakes, crocodiles, and alligators have vertical slits which are useful for ...
The pupil function or aperture function describes how a light wave is affected upon transmission through an optical imaging system such as a camera, microscope, or the human eye. More specifically, it is a complex function of the position in the pupil [ 1 ] or aperture (often an iris ) that indicates the relative change in amplitude and phase ...
Human eye pigmentation in Europe Among human phenotypes, blue-green-gray eyes are a relatively rare [citation needed] eye color and the exact color is often perceived to vary according to its surroundings. The iris is usually strongly pigmented, with the color typically ranging between brown, hazel, green, gray, and blue.
In brighter conditions, the pupil constricts, blocking the more peripheral rays and minimizing the effect of spherical aberration. As the pupil enlarges, more peripheral rays enter the eye and the focus shifts anteriorly, making the patient slightly more myopic in low-light conditions.
In March, a mother was horrified to find a pedophile symbol on a toy she bought for her daughter. Although the symbol was not intentionally placed on the toy by the company who manufactured the ...