Description
Paraxial thin-lens vergence transfer F/(1-dF) through signed distance d, without a patient vertex-distance prescription.
Optical calculations distinguish lens power in diopters, prism notation, angular axes, geometric distances, and visual-acuity reporting scales. Sign conventions and length units are especially important when a formula combines power with decentration or vertex distance. A supplied model term is separate from a validated visual test or prescription.
Paraxial thin-lens vergence transfer F/(1-dF) through signed distance d, without a patient vertex-distance prescription.
When to use this tool
Use Optometric Trial Frame Vertex Reference when you need this explicit optical, chart, frame, axis, or reference conversion with compatible supplied units.
How to use the tool and how it works
- Enter lensPower, lensToReferenceMeters. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read effectivePower, denominator. Use the output convention below.
Require denominator=1-lensToReferenceMeters*lensPower to be nonzero. Return effectivePower=lensPower/denominator and denominator.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| lensPower | Lens power in diopters. | Required. Finite number. |
| lensToReferenceMeters | Signed separation in meters under the vergence-transfer convention. | Required. Finite number. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| effectivePower | Effective Power | Required. Finite number. |
| denominator | Denominator or exact integer denominator text under the stated sign restriction. | Required. Finite number. |
{
"input": {
"lensPower": 10,
"lensToReferenceMeters": 0.01
},
"output": {
"effectivePower": 11.11111111111111,
"denominator": 0.9
}
}Limitations and assumptions
- Lens power is diopters and separation is signed meters under this transfer convention. This is an ideal paraxial single-lens vergence relation, not a complete thick-lens model, prescription conversion, or patient-specific fitting recommendation.
- 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 appropriate complete optical or measurement model when a scalar term is insufficient. Verify power, axis, length, notation, and reference conventions before applying the result within a broader assessment.
References
Similar or alternative tools
- Lens Base Curve Supplied Index Crosswalk
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- Lens Thickness Optical Path Factor
Uniform-index slab optical path and excess over a supplied surrounding medium, not a full crystalline-lens model.