Description
Compare explicit total and monocular distance records, without selecting a spectacle fit or determining patient measurements.
Vision research uses stimulus angles, chart notations, image scales, viewing distances, coordinate origins, and observation windows. These quantities have different denominators and measurement conventions. A conversion or support share does not independently establish a visual measurement or its clinical interpretation.
Compare explicit total and monocular distance records, without selecting a spectacle fit or determining patient measurements.
When to use this tool
Use Ophthalmology Interpupillary Half Distance Offset when you need this image, stimulus, notation, coordinate, or observation component for supplied research data.
How to use the tool and how it works
- Enter totalDistance, rightDistance, leftDistance. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read halfDistance, rightOffset, leftOffset, closureGap. Use the output convention below.
For nonnegative totalDistance, rightDistance, and leftDistance return halfDistance=total/2, each side's offset from that half, and closureGap=rightDistance+leftDistance-totalDistance.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| totalDistance | Total Distance | Required. Finite number; minimum 0. |
| rightDistance | Right Distance | Required. Finite number; minimum 0. |
| leftDistance | Left Distance | Required. Finite number; minimum 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| halfDistance | Half Distance | Required. Finite number. |
| rightOffset | Right Offset | Required. Finite number. |
| leftOffset | Left Offset | Required. Finite number. |
| closureGap | Sum of two supplied side distances minus the supplied total. | Required. Finite number. |
{
"input": {
"totalDistance": 64,
"rightDistance": 33,
"leftDistance": 31
},
"output": {
"halfDistance": 32,
"rightOffset": 1,
"leftOffset": -1,
"closureGap": 0
}
}Limitations and assumptions
- All lengths need one unit and reference convention. Side distances are not required to sum to the total, so the discrepancy is retained; no pupil detection, anatomical measurement, or fitting decision is made.
- 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 calibrated acquisition and a documented visual or imaging protocol for complete interpretation. Confirm the reporting notation, viewing geometry, image scale, and support of the underlying observations.
References
Similar or alternative tools
- Spectacle Asymmetric Frame Decentration Pair
Explicit planar model decentration and conservative circular-blank budget, without selecting spectacle fitting measurements.
- Frame Decentration Reference Gap
Compare supplied bench frame and pupil coordinates in one axis basis.