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Related Experiment Video

Updated: Dec 30, 2025

Author Spotlight: Establishing a Practical and Cost-Effective Protocol for Corneal Sensitivity Testing in Clinical Settings
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Author Spotlight: Establishing a Practical and Cost-Effective Protocol for Corneal Sensitivity Testing in Clinical Settings

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Pupil response to noxious corneal stimulation.

Emmanuel B Alabi1, Trefford L Simpson1

  • 1University of Waterloo, School of Optometry and Vision Science, Waterloo, ON, Canada.

Plos One
|January 18, 2020
PubMed
Summary

Ocular somatosensory-autonomic reflexes were studied by applying painful stimuli to the cornea. Pupil dilation increased with stimulus intensity, and females showed greater responses than males at higher intensities.

Area of Science:

  • Ophthalmology
  • Neuroscience
  • Autonomic Nervous System Research

Background:

  • Ocular somatosensory-autonomic reflexes are crucial for maintaining eye homeostasis.
  • Understanding these reflexes is key to diagnosing and managing ocular conditions.

Purpose of the Study:

  • To investigate pupil responses to nociceptive (painful) corneal stimuli.
  • To characterize the relationship between stimulus intensity and pupil dilation.

Main Methods:

  • Mechanical and chemical stimuli were applied to the central cornea of healthy subjects.
  • Pupil diameter was measured using digital cameras and ImageJ software.
  • Statistical analyses included dependent t-tests and repeated measures ANOVA.

Main Results:

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  • Pupil diameter increased significantly with increasing corneal stimulus intensity.
  • No significant difference in pupil response was observed between stimulated and unstimulated eyes.
  • Females exhibited greater pupil dilation than males at higher stimulus intensities.

Conclusions:

  • Pupil response is a reliable indicator of nociceptive stimulus intensity in the cornea.
  • This research provides a basis for understanding local neural circuitry of ocular pain and autonomic responses.
  • Pupil measurements, alongside redness and tearing, offer accurate, separable indicators of painful stimulus intensity.