Description
Express a retinal image measurement in supplied disc-diameter units.
Eye records preserve laterality, reference axes, chart distance, calibration provenance and geometric scale. Disc-diameter units are a relative image scale, not a physical length, and cylinder sign differs from a full prescription transformation. Supplied labels and conversions do not inspect an eye, detect disease or choose care.
Express a retinal image measurement in supplied disc-diameter units.
When to use this tool
Use Retina Disc Diameter Scale when you already have measuredPixels, discPixels and need to express a retinal image measurement in supplied disc-diameter units.
How to use the tool and how it works
- Enter measuredPixels, discPixels. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read discDiameterUnits. Use the output convention below.
Require measuredPixels>=0 and discPixels>0; return measuredPixels/discPixels.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| measuredPixels | Measured Pixels | Required. Finite number; minimum 0. |
| discPixels | Disc Pixels | Required. Finite number; strictly above 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| discDiameterUnits | Measured pixels/disc pixels, a dimensionless relative image scale. | Required. Finite number. |
{
"input": {
"measuredPixels": 300,
"discPixels": 120
},
"output": {
"discDiameterUnits": 2.5
}
}Limitations and assumptions
- Assumes matching image scale; no physical disc diameter, retinal anatomy, diagnosis or calibration accuracy is inferred.
- 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
Review the original image calibration, refraction convention and chart-distance record for substantive measurements. Use complete optical or image geometry when physical scale or clinical interpretation is required; relative disc units and axis labels preserve narrower conventions.
References
Similar or alternative tools
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