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NCT Number: NCT05931250

Alternating and Direct Current Stimulation for Neuropathic Eye Pain

The goal of this clinical intervention is to test if two forms of transcranial current stimulation, transcranial direct current stimulation (tDCS) or transcranial alternating current stimulation (tACS) can alleviate neuropathic eye pain in a sample of 20 patients.

The main aims are:

* Test if tDCS/tACS can alleviate neuropathic eye pain and/or other cerebral symptoms: brain fatigue, migraine, light sensitivity, etc. * Test if one stimulation method is superior to the other Patients will be treated for a total of fifteen 30-minute stimulation sessions, three times a day over a five-day period, each stimulation separated by approximately 4 hours, with either active tACS or tDCS over the scalp corresponding to primary sensory and motor areas.

The patients will have questionnaires to monitor subjective experiences and pupillometry before and after treatment to monitor experimental outcomes.

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Key information

Conditions

Eye Pain Brain Diseases Brain Injuries Central Nervous System Diseases Cerebral Injury Cranial Nerve Diseases Craniocerebral Trauma Eye Diseases Eye Manifestations Nervous System Diseases Neurologic Manifestations Neuropathy, Optic Optic Nerve Diseases Pain Pathological Conditions, Signs and Symptoms Signs and Symptoms Trauma, Nervous System Wounds and Injuries

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Eye Clinic, University Hospital in Linköping

Linköping, Other / Non-US, 58183, Sweden

About this study

Brief Summary sufficient

Who can participate

Healthy volunteers accepted: No

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

Inclusion criteria

  • persistent eye pain for at least 6 months
  • average eye pain intensity of 4 or more on a 0-10 numerical rating scale
  • naive to transcranial stimulation
  • eye pain having neuropathic-like characteristics

Exclusion criteria

  • contraindication to transcranial stimulation (i.e., pacemaker, cardioverter defibrillator, neuro-stimulation (brain or spinal cord), bone growth stimulations, indwelling blood pressure monitors, epilepsy, pregnancy)
  • presence of ocular diseases that are the likely cause of pain (i.e., corneal and conjunctival scarring, corneal edema, uveitis, iris transillumination defects, etc.)
  • current participation in another study with an investigational drug or device within one month prior to screening

Treatment and study plan

DC-Stimulator Plus (NeuroConn GmbH, Germany)

Device

Transcranial alternating current stimulation

Sooma direct current stimulator (Sooma, Finland)

Device

Transcranial direct current stimulation

Primary outcomes

  1. Change from baseline subjective pain via neuropathic pain symptom inventory for the eye (NPSI-eye) at 1 week

    Time frame: through treatment completion, 1 week

    Assesses pain related symptoms on a scale from 0 indicating no pain (better outcome) to10 indicating worst pain imaginable (worse outcome)

  2. Change from baseline subjective pain via neuropathic pain symptom inventory for the eye (NPSI-eye) at 2 weeks

    Time frame: through treatment completion, 2 weeks

    Assesses pain related symptoms on a scale from 0 indicating no pain (better outcome) to10 indicating worst pain imaginable (worse outcome)

  3. Change from baseline subjective pain via neuropathic pain symptom inventory for the eye (NPSI-eye) at 1 month

    Time frame: through treatment completion, 1 month

    Assesses pain related symptoms on a scale from 0 indicating no pain (better outcome) to10 indicating worst pain imaginable (worse outcome)

  4. Change from baseline subjective pain effect experiences via Defense and Veteran Pain Rating Scale (DVPRS) at 1 week

    Time frame: through treatment completion, 1 week

    Assesses pain related symptoms effecting sleep, stress, disposition, life quality, on a scale from 0 indicating no effect (better outcome) to10 indicating maximum effect (worse outcome)

  5. Change from baseline subjective pain effect experiences via Defense and Veteran Pain Rating Scale (DVPRS) at 2 weeks

    Time frame: through treatment completion, 2 weeks

    Assesses pain related symptoms effecting sleep, stress, disposition, life quality, on a scale from 0 indicating no effect (better outcome) to10 indicating maximum effect (worse outcome)

  6. Change from baseline subjective pain effect experiences via Defense and Veteran Pain Rating Scale (DVPRS) at 1 month

    Time frame: through treatment completion, 1 month

    Assesses pain related symptoms effecting sleep, stress, disposition, life quality, on a scale from 0 indicating no effect (better outcome) to10 indicating maximum effect (worse outcome)

  7. Change from baseline subjective mental symptoms via Mental Fatigue Scale (MFS) at 1 week

    Time frame: through treatment completion, 1 week

    Assesses mental symptoms on a scale from 0 indicating no effect (better outcome) to 3 indicating extreme effect (worse outcome)

  8. Change from baseline subjective mental symptoms via Mental Fatigue Scale (MFS) at 2 weeks

    Time frame: through treatment completion, 2 weeks

    Assesses mental symptoms on a scale from 0 indicating no effect (better outcome) to 3 indicating extreme effect (worse outcome)

  9. Change from baseline subjective mental symptoms via Mental Fatigue Scale (MFS) at 1 month

    Time frame: through treatment completion, 1 month

    Assesses mental symptoms on a scale from 0 indicating no effect (better outcome) to 3 indicating extreme effect (worse outcome)

  10. Change from baseline subjective ocular symptoms and symptom frequency via custom ocular pain questionnaire at 1 week

    Time frame: through treatment completion, 1 week

    Ocular pain questionnaire using a visual analog scale with 0 indicating no pain (better outcome) and 10 indicating extreme pain (worse outcome) and frequency measure from 0% indicating never occurring (better outcome) to 100% indicating always occurring (worse outcome)

  11. Change from baseline subjective ocular symptoms and symptom frequency via custom ocular pain questionnaire at 2 weeks

    Time frame: through treatment completion, 1 month

    Ocular pain questionnaire using a visual analog scale with 0 indicating no pain (better outcome) and 10 indicating extreme pain (worse outcome) and frequency measure from 0% indicating never occurring (better outcome) to 100% indicating always occurring (worse outcome)

  12. Change from baseline subjective ocular symptoms and symptom frequency via custom ocular pain questionnaire at 1 month

    Time frame: through treatment completion, 1 month

    Ocular pain questionnaire using a visual analog scale with 0 indicating no pain (better outcome) and 10 indicating extreme pain (worse outcome) and frequency measure from 0% indicating never occurring (better outcome) to 100% indicating always occurring (worse outcome)

  13. Number of patients with treatment-related adverse events as assessed by ocular pain questionnaire

    Time frame: through treatment completion, 1 month

    Ocular pain questionnaire using a visual analog scale with 0 indicating no pain (better outcome) and 10 indicating extreme pain (worse outcome) and frequency measure from 0% indicating never occurring (better outcome) to 100% indicating always occurring (worse outcome)

  14. Change from baseline pupil diameter in millimeters at 1 week

    Time frame: through treament completion, 1 week

    Minimum and maximum pupil diameter in millimeters

  15. Change from baseline pupil velocity in millimeters per second at 1 week

    Time frame: through treament completion, 1 week

    Pupil change velocity in millimeters per second

  16. Change from baseline pupil latency in milliseconds at 1 week

    Time frame: through treament completion, 1 week

    Pupil latency latency in milliseconds

Secondary outcomes

  1. Treatment compliance rate

    Time frame: through study completion, 1 year

    Evaluation of completed treatment from a total of 15

Other outcomes

  1. Beta coefficients for participant demographics (sex, age, race/ethnicity) in regression model predicting adherence to treatment protocol

    Time frame: through study completion, 1 year

    Exploratory regression analysis to identify associations between demographic variables and number of treatment sessions completed

  2. Beta coefficients for participant demographics (sex, age, race/ethnicity) in regression model predicting change in pain (Numerical Rating Scale)

    Time frame: through study completion, 1 year

    Exploratory regression analysis to identify associations between demographic variables and change in pain ratings (before vs. after stimulation treatment)

Sponsors and collaborators

Lead sponsor

Neil Lagali

Other

Collaborators

  • Linkoeping University
  • Region Östergötland
  • University Hospital, Linkoeping

Registry information

Official study title

Alternating and Direct Current Stimulation for the Treatment of Chronic Neuropathic Eye Pain and Cerebral Symptoms: a Pilot Study

Important dates

Study start
2023
Primary completion
2024
Study completion
2024
First posted
Jul 5, 2023
Registry last updated
Jul 13, 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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