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  2. 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. 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.

  3. Aniseikonia - Wikipedia

    en.wikipedia.org/wiki/Aniseikonia

    Aniseikonia. Aniseikonia is an ocular condition where there is a significant difference in the perceived size of images. It can occur as an overall difference between the two eyes, or as a difference in a particular meridian. [1] If the ocular image size in both eyes are equal, the condition is known as iseikonia. [2]

  4. Inverse problem in optics - Wikipedia

    en.wikipedia.org/wiki/Inverse_problem_in_optics

    The inverse problem in optics (or the inverse optics problem [1]) refers to the fundamentally ambiguous mapping between sources of retinal stimulation and the retinal images that are caused by those sources. [2] For example, the size of an object, the orientation of the object, and its distance from the observer are conflated in the retinal image.

  5. Entoptic phenomenon - Wikipedia

    en.wikipedia.org/wiki/Entoptic_phenomenon

    Entoptic phenomenon. Entoptic phenomena (from Ancient Greek ἐντός (entós) 'within' and ὀπτικός (optikós) 'visual') are visual effects whose source is within the human eye itself. (Occasionally, these are called entopic phenomena, which is probably a typographical mistake.) In Helmholtz 's words: "Under suitable conditions light ...

  6. Macular degeneration - Wikipedia

    en.wikipedia.org/wiki/Macular_degeneration

    8.7% global prevalence in 2020 [ 2] Macular degeneration, also known as age-related macular degeneration ( AMD or ARMD ), is a medical condition which may result in blurred or no vision in the center of the visual field. [ 1] Early on there are often no symptoms. [ 1] Over time, however, some people experience a gradual worsening of vision that ...

  7. Perspective distortion - Wikipedia

    en.wikipedia.org/wiki/Perspective_distortion

    Perspective distortion takes two forms: extension distortion and compression distortion, also called wide-angle distortion and long-lens or telephoto distortion,[ 1] when talking about images with the same field size. Extension or wide-angle distortion can be seen in images shot from close using a wide-angle lens (with an angle of view wider ...

  8. What Is Ear Candling and Is It Safe? - AOL

    www.aol.com/lifestyle/ear-candling-safe...

    Conclusion. In conclusion, the evidence is clear: ear candling is neither practical nor safe and has been shown to cause injury in some cases. If you're looking for ways to clean your ears or ...

  9. Normal lens - Wikipedia

    en.wikipedia.org/wiki/Normal_lens

    A normal lens typically has an angle of view that is close to one radian (~57.296˚) of the optical system's image circle. [citation needed] For 135 format (24 x 36 mm), with an escribed image circle diameter equal to the diagonal of the frame (43.266 mm), the focal length that has an angle of one radian of the inscribed circle is 39.6 mm; the focal length that has an angle of one radian of ...