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  2. Iris (anatomy) - Wikipedia

    en.wikipedia.org/wiki/Iris_(anatomy)

    The iris (pl.: irides or irises) is a thin, annular structure in the eye in most mammals and birds that is responsible for controlling the diameter and size of the pupil, and thus the amount of light reaching the retina. In optical terms, the pupil is the eye's aperture, while the iris is the diaphragm. Eye color is defined by the iris.

  3. Pupil - Wikipedia

    en.wikipedia.org/wiki/Pupil

    The pupil is a hole located in the center of the iris of the eye that allows light to strike the retina. [1] It appears black because light rays entering the pupil are either absorbed by the tissues inside the eye directly, or absorbed after diffuse reflections within the eye that mostly miss exiting the narrow pupil.

  4. Human eye - Wikipedia

    en.wikipedia.org/wiki/Human_eye

    An area termed the limbus connects the cornea and sclera. The iris is the pigmented circular structure concentrically surrounding the centre of the eye, the pupil, which appears to be black. The size of the pupil, which controls the amount of light entering the eye, is adjusted by the iris' dilator and sphincter muscles.

  5. List of optometric abbreviations - Wikipedia

    en.wikipedia.org/wiki/List_of_optometric...

    Pupils equal, round, reactive to light and accommodation PH Pinhole see Pinhole occluder and Visual_acuity#Legal_definitions: PHNI Pinhole No Improvement see Pinhole occluder and Visual_acuity#Legal_definitions: PHVA Pinhole Visual Acuity: PL Perception of light POH / PrOH Previous ocular history PPA Peri-papillary atrophy Pt Patient RAPD

  6. Aperture - Wikipedia

    en.wikipedia.org/wiki/Aperture

    The iris is analogous to the diaphragm, and the pupil (which is the adjustable opening in the iris) the aperture. Refraction in the cornea causes the effective aperture (the entrance pupil in optics parlance) to differ slightly from the physical pupil diameter.

  7. Retina vs. Iris Recognition: Similarities and Differences - AOL

    www.aol.com/news/2016-02-22-retina-vs-iris...

    Besides fingerprint and facial recognition, eye scanning is one of the most highly mentioned biometric modalities these days. As the security market rapidly increases, it is expected that eye ...

  8. Intraocular muscles - Wikipedia

    en.wikipedia.org/wiki/Intraocular_muscles

    The pupillary sphincter muscle and pupillary dilator muscle control the iris to adjust the size of the pupil to adjust how much light enters into the eye. The pupillary dilator muscle increases the pupillary diameter and it is arranged radially, but the pupillary sphincter muscle is responsible for the constriction of the pupil's diameter and ...

  9. Eye - Wikipedia

    en.wikipedia.org/wiki/Eye

    Muscles around the iris change the size of the pupil, regulating the amount of light that enters the eye [3] and reducing aberrations when there is enough light. [4] The eyes of most cephalopods , fish , amphibians and snakes have fixed lens shapes, and focusing is achieved by telescoping the lens in a similar manner to that of a camera .