Pupillary Light Reflex Latency

Find the interpolated first pupil constriction threshold crossing after a stimulus using supplied baseline and amplitude criterion; missing crossings return an error, not a fabricated latency.

Description

Pupillary constriction onset can be defined as reaching a chosen decrease from a supplied baseline.

Pupillary constriction onset can be defined as reaching a chosen decrease from a supplied baseline. The time threshold and baseline are explicit caller choices.

The tool returns onsetTimeMs (onset time ms); latencyMs (latency ms). Input measurements and model parameters are supplied by the caller; the tool computes the stated summary rather than acquiring those measurements.

When to use Pupillary Light Reflex Latency

Use Pupillary Light Reflex Latency when you already have timesMs, diametersMm, stimulusTimeMs, baselineDiameterMm, requiredConstrictionMm and want onsetTimeMs, latencyMs. This is useful for checking a supplied calculation, documenting a measurement convention, or comparing observations prepared on the same basis.

How to use Pupillary Light Reflex Latency and understand its results

Enter timesMs, diametersMm, stimulusTimeMs, baselineDiameterMm, requiredConstrictionMm using the field table below. Match the units, ordering and data boundaries described in the calculation.
Run the tool after checking the stated bounds and matching paired observations or categories. A malformed request gives a tool error rather than a usable measurement.
Read onsetTimeMs, latencyMs. Use the calculation and interpretation below to distinguish amounts, ratios, signs and decision flags where applicable.
Review the supplied parameters and assumptions before using the result in a report or comparing it with another observation.

Input field	Meaning	Value type and bounds	Requirement
timesMs	Times ms	list of number	Required
diametersMm	Diameters mm	list of number	Required
stimulusTimeMs	Stimulus time ms	number	Required
baselineDiameterMm	Baseline diameter mm	number	Required
requiredConstrictionMm	Required constriction mm	number	Required

Use positive diameters, baseline and required decrease. Interpolate the first downward crossing from the stimulus, rejecting left-censored or absent crossings.

thresholdDiameter = baseline−requiredConstriction; latency = first downward crossing−stimulusTime

The symbols refer to the supplied quantities or generated values described above; unit conversions and comparison boundaries follow the stated implementation.

json

{
  "input": {
    "timesMs": [
      0,
      100,
      200,
      300
    ],
    "diametersMm": [
      4,
      4,
      3,
      2
    ],
    "stimulusTimeMs": 100,
    "baselineDiameterMm": 4,
    "requiredConstrictionMm": 0.5
  },
  "output": {
    "onsetTimeMs": 150,
    "latencyMs": 50
  }
}

Limitations and assumptions

Baseline is not estimated from the trace. Artifact removal and physiological interpretation are external; an unreachable threshold fails.

Numerical inputs must be finite. The tool checks its declared input shape and calculation constraints; those checks do not verify the quality, calibration or representativeness of the supplied observations.

Alternative or Complementary methods

Pupillary Unrest Index: Compute absolute pupil diameter path change per minute from uniformly processed samples; cadence, smoothing and blink interpolation materially affect this unrest measure. Saccade Latency: Interpolate the first supplied eye-speed threshold crossing after a cue; blink rejection and direction classification are not inferred.

Methodological background: Digital Library of Mathematical Functions: Quadrature.^[1]

References

Digital Library of Mathematical Functions: Quadrature — National Institute of Standards and Technology

Similar or alternative tools

Pupillary Unrest Index
Compute absolute pupil diameter path change per minute from uniformly processed samples; cadence, smoothing and blink interpolation materially affect this unrest measure.
Saccade Latency
Interpolate the first supplied eye-speed threshold crossing after a cue; blink rejection and direction classification are not inferred.