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Completed

NCT Number: NCT02628314

Reliability of Pupil Response to Acute Pain

The purpose of this research study is to test whether researchers can reliably measure the response pupils have when an acute painful stimulus is experienced. Changes in the size of the pupil of the eye can be an indicator of brain activity in a region of the brain that is important for feeling pain.

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Key information

Conditions

Pain Arthritis Joint Diseases Musculoskeletal Diseases Neurologic Manifestations Osteoarthritis Pathological Conditions, Signs and Symptoms Rheumatic Diseases Signs and Symptoms

Age range

18 year–70 year

Sex eligibility

All sexes

Study type

Observational

Primary location

Wake Forest Baptist Medical Center

Winston-Salem, North Carolina, 27157, United States

About this study

There is strong rationale to support a role for locus coeruleus (LC) responsivity to acute painful stimuli in regulating speed of recovery after surgery and for LC responsivity as a mechanistic link explaining the risks for slow recovery from weak Conditioned Pain Modulation (CPM), catastrophizing cognitive style, and low enzyme activity catecholamine-O-methyltransferase (COMT) genotype. Preliminary data show feasibility to perform the proposed study.

Primary Hypothesis: An observational study of pupil responses to noxious stimuli shows strong intra-individual reliability over 8 weeks.

Key secondary hypotheses: Compared to individuals homozygous for val at the val158met site of the catecholamine-O-methyltransferase (COMT) gene, those homozygous for met will show smaller pupil responses to noxious stimuli and weaker CPM.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Adult (18-70)
  • Pain from hip or knee arthritis of moderate intensity
  • American Society of Anesthesiologists physical status 1-3

Exclusion criteria

  • Inability to complete study questionnaires
  • Pregnancy
  • Litigation or workers compensation related to hip or knee pain
  • Taking > 50 mg morphine equivalents/day
  • History of Raynaud's disease of the feet
  • Psychotic disorder or a recent psychiatric hospitalization
  • History of eye surgery or topical eye medications that would would directly affect pupil diameter

Treatment and study plan

Primary outcomes

  1. Percentage of change in pupil diameter

    Time frame: 8 weeks

    pupil diameter in response to 5 second presentation of noxious heat stimuli

  2. Change from Baseline Verbal Pain Scores

    Time frame: 8 weeks

    Verbal pain scores will be obtained during stimulus presentation

Sponsors and collaborators

Lead sponsor

Wake Forest University Health Sciences

Other

Registry information

Important dates

Study start
2015
Primary completion
2025
Study completion
2025
First posted
Dec 11, 2015
Registry last updated
Apr 29, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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