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  2. Presbyopia - Wikipedia

    en.wikipedia.org/wiki/Presbyopia

    Presbyopia is a physiological insufficiency of optical accommodation associated with the aging of the eye; it results in progressively worsening ability to focus clearly on close objects. [4] Also known as age-related farsightedness [ 5 ] (or as age-related long sight in the UK [ 6 ] ), it affects many adults over the age of 40.

  3. Refractive error - Wikipedia

    en.wikipedia.org/wiki/Refractive_error

    A distant object is defined as an object located beyond 6 meters (20 feet) from the eye. [citation needed] When an object is located close to the eye, the rays of light from this object no longer approach the eye parallel to each other. Consequently, the eye must increase its refractive power to bring those rays of light together on the retina.

  4. Visual agnosia - Wikipedia

    en.wikipedia.org/wiki/Visual_agnosia

    At an associative level, the meaning of an object is attached to the perceptual representation and the object is identified. [2] If a person is unable to recognize objects because they cannot perceive correct forms of the objects, although their knowledge of the objects is intact (i.e. they do not have anomia), they have apperceptive agnosia ...

  5. Accommodation (vertebrate eye) - Wikipedia

    en.wikipedia.org/wiki/Accommodation_(vertebrate_eye)

    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 ...

  6. Farsightedness - Wikipedia

    en.wikipedia.org/wiki/Farsightedness

    If the brain never learns to see objects in detail, then there is a high chance of one eye becoming dominant. The result is that the brain will block the impulses of the non-dominant eye. In contrast, the child with myopia can see objects close to the eye in detail and does learn at an early age to see objects in detail. [medical citation needed]

  7. Accommodative insufficiency - Wikipedia

    en.wikipedia.org/wiki/Accommodative_insufficiency

    AI is generally considered separate from presbyopia, but mechanically both conditions represent a difficulty engaging the near vision system (accommodation) to see near objects clearly. Presbyopia is physiological insufficiency of accommodation due to age related changes in lens (decreased elasticity and increased hardness) and ciliary muscle ...

  8. Human eye - Wikipedia

    en.wikipedia.org/wiki/Human_eye

    Following an object moving at constant speed is relatively easy, though the eyes will often make saccades to keep up. The smooth pursuit movement can move the eye at up to 100°/s in adult humans. It is more difficult to visually estimate speed in low light conditions or while moving, unless there is another point of reference for determining ...

  9. Fixation (visual) - Wikipedia

    en.wikipedia.org/wiki/Fixation_(visual)

    Ocular drift is the fixational eye movement characterized by a smoother, slower, roaming motion of the eye when fixed on an object. The exact movement of ocular drift is often compared to Brownian motion, which is the random motion of a particle suspended in fluid as a result of its collision with the atoms and molecules that comprise that fluid.