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  2. Eyeglass prescription - Wikipedia

    en.wikipedia.org/wiki/Eyeglass_prescription

    SPH, CYL, and AXIS are values for describing the power of the lens using plus cylinder or minus cylinder notation. ADD is an abbreviation for Near Addition. This is the additional refractive power to be combined, or added, to the distance power to achieve the ideal near power.

  3. List of optometric abbreviations - Wikipedia

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

    Dioptres cylinder DNA: Did not attend DOB: Date of birth DS: Dioptres sphere DV: Distance vision DVD: Dissociated vertical deviation EF: Eccentric fixation FB: Foreign body FD: Fixation disparity FF: Foveal fixation FHG: Family history of glaucoma: FMH: Family medical history FOH: Family ocular history F/U: Follow up appointment GH: General ...

  4. Lensmeter - Wikipedia

    en.wikipedia.org/wiki/Lensmeter

    The parameters appraised by a lensmeter are the values specified by an ophthalmologist or optometrist on the patient's prescription: sphere, cylinder, axis, add, and in some cases, prism. The lensmeter is also used to check the accuracy of progressive lenses , and is often capable of marking the lens center and various other measurements ...

  5. Jackson cross cylinder - Wikipedia

    en.wikipedia.org/wiki/Jackson_cross_cylinder

    Jackson cross cylinder of +/- 0.25 diopter. Jackson cross cylinder is a single low power lens, which is a combination of a plus cylinder and a minus cylinder of equal power with axis perpendicular to each other, with a handle placed between the two axes at 45 degrees.

  6. Phoropter - Wikipedia

    en.wikipedia.org/wiki/Phoropter

    It included a Stevens Phorometer for measuring phorias, and a disc of auxiliary spherical lenses on the back, giving it a range of -12.00 to +12.00. To extend the range, there were clips on the front of each eye hole for the insertion of hand held sphere or cylinder trial lenses, with a mechanism to rotate the axis with the thumb.

  7. Engineering drawing abbreviations and symbols - Wikipedia

    en.wikipedia.org/wiki/Engineering_drawing...

    Same definition as the bolt circle diameter BHCS: button head cap screw: Like an SHCS but with a button head. BHN: Brinell hardness number: BoM or BOM: bill of materials: Also called a list of materials (LM or L/M). Overlaps a lot in concept with a parts list (PL or P/L). There is no consistently enforced distinction between an L/M, a BoM, or a ...

  8. Vector fields in cylindrical and spherical coordinates

    en.wikipedia.org/wiki/Vector_fields_in...

    Note: This page uses common physics notation for spherical coordinates, in which is the angle between the z axis and the radius vector connecting the origin to the point in question, while is the angle between the projection of the radius vector onto the x-y plane and the x axis. Several other definitions are in use, and so care must be taken ...

  9. Cylindrical coordinate system - Wikipedia

    en.wikipedia.org/wiki/Cylindrical_coordinate_system

    A cylindrical coordinate system is a three-dimensional coordinate system that specifies point positions by the distance from a chosen reference axis (axis L in the image opposite), the direction from the axis relative to a chosen reference direction (axis A), and the distance from a chosen reference plane perpendicular to the axis (plane ...