A window to the brain? eye signals may track dopamine
NCT ID NCT07748715
First seen Aug 06, 2026 · Last updated Aug 13, 2026 · Updated 3 times
Summary
This study explores whether electrical signals from the eye and brain can serve as a noninvasive marker of dopamine activity. About 50 adults—half with Parkinson's disease and half without—will have their eye and brain responses measured using sensors on the skin. People with Parkinson's will be tested before and after taking their usual medication, while healthy volunteers will receive a single dose of levodopa/carbidopa eye drops in one eye and a placebo in the other. The goal is to see if blue-light responses change with dopamine levels, which could lead to a simpler way to monitor conditions like Parkinson's.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- Active substance
- Levodopa/carbidopa eye drops and oral levodopa/carbidopa (Sinemet)
- What this could lead to
- If successful, this could lead to a simple, noninvasive test for dopamine function, potentially aiding in monitoring Parkinson's disease.
- What could go wrong
- This is an early-stage study with a small number of participants. The eye and brain signals may not reliably reflect dopamine levels, and the eye drop formulation is not FDA-approved for this use.
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Study facts
What this study's own registry entry says, in plain language.
- Participants
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About 50 people
The number the study aims to enrol. It can still change while the study runs.
- Expected to start
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Oct 2026
An estimate. Start dates often move.
- Expected to finish
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Sep 2027
An estimate. End dates often move.
- Lead sponsor
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Other sponsor
The registry's catch-all category, for sponsors it does not file as a company, a government agency, or a research network.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
Who is studied
Adults ages 18 years and above. Adults will be either healthy controls or have confirmed diagnosis of Parkinson's disease.
- Ages
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18 years and older
- Sex
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Anyone
- Healthy volunteers
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Accepted
You do not need to have the condition being studied to take part.
Show the full entry requirements Hide the full entry requirements
Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
Inclusion Criteria: * Parkinson's subjects will have received physician verified diagnosis of the disease and be on a dopaminergic medication for at least 3 months Exclusion Criteria: * Any movement, strength, or balance assessments that may pose a potential risk for injury * Individuals with a history of photosensitive epilepsy or seizure activity triggered by visual stimuli * Current use of antipsychotics, stimulants, or other medications known to affect central dopaminergic transmission * Pregnancy * Recent ocular surgery * Phenylketonuria * (PD participants) not cognitively intact and not able to consent for themselves * (non-PD subjects) a pre-screening survey will assess medication use and neurological history * Ophthalmologic or visual system conditions that may interfere with stimulus delivery or retinal function. These include significant cataract (defined as LOCS III ≥ NC2/NO2 or any media opacity that precludes adequate delivery of visual stimuli to the retina), active retinal or macular pathology (including age-related macular degeneration with significant drusen or geographic atrophy, diabetic retinopathy, retinal vein occlusion, or epiretinal membrane with foveal involvement), glaucoma, or any optic neuropathy. * Individuals with congenital color vision deficiencies, particularly tritan-spectrum defects * Ocular surgery within the past three months * Use of medications known to affect retinal electrophysiology (e.g., chronic hydroxychloroquine, vigabatrin, deferoxamine, or isotretinoin) * History of photosensitive epilepsy or visually triggered seizures (especially relevant given the use of bright visual stimuli and potential flicker paradigms)
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Conditions
The condition(s) this trial relates to.
As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
How to take part
Only the study team decides who joins. These are the ways to reach them.
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The official record
ClinicalTrials.gov lists the study team's own contact details, including names and phone numbers. We don't republish those.
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A doctor treating you
A doctor who knows your case can contact a study site on your behalf, and can tell you whether this study is worth pursuing at all.
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