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  2. Dioptre - Wikipedia

    en.wikipedia.org/wiki/Dioptre

    A dioptre ( British spelling) or diopter ( American spelling ), symbol dpt, is a unit of measurement with dimension of reciprocal length, equivalent to one reciprocal metre, 1 dpt = 1 m−1. It is normally used to express the optical power of a lens or curved mirror, which is a physical quantity equal to the reciprocal of the focal length ...

  3. Prism correction - Wikipedia

    en.wikipedia.org/wiki/Prism_correction

    Prism correction is measured in prism dioptres. A prescription that specifies prism correction will also specify the "base". The base is the thickest part of the lens and is opposite from the apex. Light will be bent towards the base and the image will be shifted towards the apex.

  4. Eyeglass prescription - Wikipedia

    en.wikipedia.org/wiki/Eyeglass_prescription

    Prism and Base Prism refers to a displacement of the image through the lens, often used to treat strabismus and other binocular vision disorders. The prism value is measured in prism diopters , and Base refers to the direction of displacement.

  5. Four prism dioptre reflex test - Wikipedia

    en.wikipedia.org/wiki/Four_prism_dioptre_reflex_test

    The Four Prism Dioptre Reflex Test (also known as the 4 PRT, or 4 Prism Dioptre Base-out Test) is an objective, non-dissociative test used to prove the alignment of both eyes (i.e. the presence of binocular single vision) by assessing motor fusion.

  6. Hirschberg test - Wikipedia

    en.wikipedia.org/wiki/Hirschberg_test

    In a person with normal ocular alignment the light reflex lies slightly nasal from the center of the cornea (approximately 11 prism dioptersor 0.5mm from the pupillary axis), as a result of the cornea acting as a temporally-turned convex mirror to the observer.

  7. Accommodative convergence - Wikipedia

    en.wikipedia.org/wiki/Accommodative_convergence

    Clinically, accommodative convergence is measured as a ratio of convergence, measured in prism diopters, to accommodation, measured in diopters of near demand. The patient is instructed to make a near target perfectly clear and their phoria is measured as the focusing demand on the eye is changed with lenses.

  8. Vertex distance - Wikipedia

    en.wikipedia.org/wiki/Vertex_distance

    Vertex distance is important when converting between contact lens and glasses prescriptions and becomes significant if the glasses prescription is beyond ±4.00 diopters (often abbreviated D).

  9. Dioptrics - Wikipedia

    en.wikipedia.org/wiki/Dioptrics

    Dioptrics is the branch of optics dealing with refraction, especially by lenses. In contrast, the branch dealing with mirrors is known as catoptrics. [1] Telescopes that create their image with an objective that is a convex lens ( refractors) are said to be "dioptric" telescopes.

  10. Amplitude of accommodation - Wikipedia

    en.wikipedia.org/wiki/Amplitude_of_accommodation

    The average amplitude of accommodation, in diopters, for a patient of a given age was estimated by Hofstetter in 1950 to be 18.5 − (0.30 * patient age in years) with the minimum amplitude of accommodation as 15 − (0.25 * age in years), and the maximum as 25 − (0.40 * age in years).

  11. Phoropter - Wikipedia

    en.wikipedia.org/wiki/Phoropter

    The major components of the phoropter are the battery of spherical and cylindrical lenses, auxiliary devices such as Maddox rods, filtered lenses, prisms, and the JCC ( Jackson cross cylinder) used for astigmatism measurement. The prismatic lenses are used to analyze binocular vision and treat orthoptic problems.