Glasses Prescription

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1. Determination of the Best Spherical Glass

  • Starting Point: Autorefractor values or old glasses values
  • Give plus lenses and ask: “Does it get worse?”
    • “No”: Continue giving plus lenses until vision worsens
    • “Yes”: Give minus lenses until vision is “the same”, then give plus lenses again until vision worsens
    • The last lens before vision worsens = best spherical glass

2. Cross-Cylinder Test 1: Axis Alignment

  • Align the handle with the axis
  • Rotate correction cylinder towards “better”
  • Cave: Larger cylinders require more precise axis alignment!

3. Cross-Cylinder Test 2: Strength Alignment

  • Align axis with axis
  • If cylinder strength is increased, enhance sphere by half the cylinder’s strength (e.g., +1 cylinder dioptre –> +0.5 dioptre)
  • If cylinder strength is decreased, reduce sphere by half the cylinder’s strength

4. Binocular Spherical Fine Adjustment

  • Separate (polarization filter) by adjusting the two number rows (e.g., right eye sees the top row, left eye the bottom row)
  • Fog with plus lenses; e.g., +0.5 or more, until both number rows appear grey/blurred
  • Consider further fogging for the eye where the number row is blacker/sharper, until both appear equally grey
  • Red-Green Test (= targeted defogging):
    • Patient looks at the green background, then briefly at the red, and indicates where the black numbers appear blacker. Initially, it’s on the red background. Then “defog” (= give more minus) until the numbers on both backgrounds appear equally black
    • Calculate test distance to infinity = add -0.25 dioptre.


  • Full correction from school age
  • In myopia, give as little minus dioptres as possible
    • Red-Green Test: if green is sharper -> overcorrected
  • In hyperopia, give as much plus dioptres as possible. Cycloplegia necessary. (Prescribe astigmatism values measured in miosis for glasses prescription)
    • Red-Green Test: if green is sharper -> undercorrected

Prescribing Reading Glasses

  • Reading glasses = Distance glasses + side-equal addition!
  • Determining the relative accommodative range:
    • Starting point: Distance glasses values. Use the near vision test chart at a standard distance of 40 cm. Patient looks at the vision line that is two rows below their maximum visual acuity (e.g., if distance vision is 1.25 -> patient looks at the 0.8 line of the near vision test chart)
    • Add plus lenses (binocularly) –> vision first improves, then worsens. Patient indicates when vision starts to worsen = maximum addition (note this)
    • Give weaker plus lenses until the first blur occurs = minimum addition (note this)
  • Near addition = 1/2 x (max addition + min addition)
  • Conversion formula depending on the distance for which the patient wants to use the glasses (e.g., for computer or TV glasses)
    • Residual Accommodation + Addition (x dioptres) = 1/d
    • If d = 80 cm –> 1/0.8 = 1.25

Children’s Glasses

Mittel- und Gegenständeliste (MiGel)

Liste des moyens et appareils (LiMA)

Elenco dei mezzi e degli apparecchi (EMAp)