Description
Calculate orthogonal principal-meridian powers from supplied sphere and cylinder.
Optical records distinguish sphere/cylinder powers, principal meridian axes, prism-base labels and eye-specific offset signs. A radial lens-blank margin is half its diametral margin under centered circular geometry. Local optical formulas and code labels do not perform refraction, verify fit or prescribe a lens.
Calculate orthogonal principal-meridian powers from supplied sphere and cylinder.
When to use this tool
Use Lens Meridian Power Pair when you already have sphereDiopters, cylinderDiopters, axisDegrees and need to calculate orthogonal principal-meridian powers from supplied sphere and cylinder.
How to use the tool and how it works
- Enter sphereDiopters, cylinderDiopters, axisDegrees. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read axisPowerDiopters, orthogonalPowerDiopters, orthogonalAxisDegrees. Use the output convention below.
Require axisDegrees in [0,180); axis power=sphere, orthogonal power=sphere+cylinder, orthogonal axis=(axis+90)%180.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| sphereDiopters | Sphere Diopters | Required. Finite number. |
| cylinderDiopters | Cylinder Diopters | Required. Finite number. |
| axisDegrees | Sphere-cylinder axis in [0,180) degrees; orthogonal axis wraps modulo 180. | Required. Finite number; minimum 0; strictly below 180. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| axisPowerDiopters | Axis Power Diopters | Required. Finite number. |
| orthogonalPowerDiopters | Orthogonal Power Diopters | Required. Finite number. |
| orthogonalAxisDegrees | Orthogonal Axis Degrees | Required. Finite number. |
{
"input": {
"sphereDiopters": -2,
"cylinderDiopters": -1,
"axisDegrees": 30
},
"output": {
"axisPowerDiopters": -2,
"orthogonalPowerDiopters": -3,
"orthogonalAxisDegrees": 120
}
}Limitations and assumptions
- Assumes the stated sphero-cylinder convention; no refraction, lens prescription, transposition or clinical suitability is determined.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use the complete verified optical prescription and lens/frame geometry for a design or fit analysis. Preserve sphere-cylinder axis and eye-specific direction conventions; a meridian sum or centered circular clearance is only one part of that calculation.
References
Similar or alternative tools
- Ophthalmic Meridian Orthogonal Pair
Return an axis and its orthogonal meridian under a half-turn convention.
- Ophthalmic Refraction Cylinder Sign Label
Label the sign and magnitude of a supplied refraction cylinder.