Actively Recruiting
Investigating the Effect of Caffeine and Alcohol on Pupil Dynamics (PAC)
Led by National University of Singapore · Updated on 2026-06-04
100
Participants Needed
1
Research Sites
26 weeks
Total Duration
On this page
Sponsors
N
National University of Singapore
Lead Sponsor
H
Home Team Science & Technology Agency (HTX)
Collaborating Sponsor
AI-Summary
What this Trial Is About
Researchers are studying how caffeine and alcohol affect the eye's pupil response to light and other physiological systems. The study aims to understand these effects and whether changes in pupil behavior can help identify recent consumption of caffeine or alcohol. This research involves healthy adults aged 30 to 50 years and looks at detailed eye and body measurements to compare caffeine, alcohol, and placebo effects. Participants attend three separate visits where they receive either caffeine (about 3 mg/kg), alcohol (to reach a blood alcohol concentration near 0.05%), or a placebo. The study uses a double-masked, randomized crossover design, meaning each participant tries all three conditions in a random order without knowing which one they are receiving. At each visit, participants take a tablet and drink a beverage matching the assigned condition, and their pupil responses to different colored lights are measured with a handheld device. Throughout each visit, participants undergo multiple assessments before and up to two hours after consumption. These include measuring pupil size and reaction to blue, red, and white light; eye movement tracking; retinal and choroidal thickness and blood flow using imaging; breath alcohol levels; and basic body measures like pulse, blood pressure, and oxygen levels. The study collects this data to identify patterns associated with caffeine and alcohol intake, which may help develop quick and non-invasive detection methods for these substances.
CONDITIONS
Brief Title
Investigating the Effect of Caffeine and Alcohol on Pupil Dynamics
Who Can Participate
Eligibility Criteria
You may qualify if you...
- Age between 30 and 50 years
- Best Corrected Visual Acuity (BCVA) of 0.20 LogMAR or better in both eyes
- Ability to understand and sign informed consent
- Willingness and ability to consume both caffeine and alcohol during the study
You will not qualify if you...
- Diagnosed eye diseases affecting vision or eye movement, such as glaucoma, macular degeneration, diabetic retinopathy, amblyopia, severe ptosis, or pupil abnormalities
- Diagnosed and unresolved neurological conditions including stroke, traumatic brain injury, brain lesions, neuropathies, demyelinating diseases, or nerve palsies
- Systemic diseases restricting caffeine or alcohol intake like hypertension, cardiovascular, liver, or kidney disease
- Use of medications that interact with caffeine or alcohol, affect alertness, or cause drowsiness
- Previous complex intraocular eye surgery excluding simple refractive surgery
- Pregnancy or breastfeeding
- History of substance abuse
- Allergies or sensitivities to caffeine or alcohol
- Shift work or recent travel across 2 or more time zones within 2 weeks
- Low caffeine or alcohol consumption (less than 100 mg caffeine per week or low AUDIT-C scores)
- Extremely frequent caffeine or alcohol consumption (more than 400 mg caffeine daily or high AUDIT-C scores)
AI-Screening
AI-Powered Screening
Complete this quick 3-step screening to check your eligibility
Your Study Journey
Duration - 2 to 4 weeks
Participants are screened for eligibility to participate in the trial.
1 visit (in-person)
Duration - Up to 3 study days total
Participants attend three separate study visits to receive caffeine, alcohol, and placebo conditions in a randomized order. At each visit, participants consume one tablet and one beverage according to the assigned condition under double-masked crossover design.
3 visits (in-person)
Duration - Each visit lasts approximately 2 hours
At each treatment visit, participants undergo repeated assessments of pupil responses, eye movements, retinal imaging, breath alcohol levels, and physiological measurements before consumption and at 30, 60, 90, and 120 minutes after consumption.
Assessments at baseline, 30, 60, 90, and 120 minutes during each of the 3 visits
Trial Site Locations
Total: 1 location
1
National University of Singapore, E7 Building, Level 7, 15 Kent Ridge Cres
Singapore, Singapore, 119276
Actively Recruiting
Research Team
V
Vicknaswari T, Bsc Optometry
N
Najiya S.K Meethal, PhD
How is the study designed?
Study Type
INTERVENTIONAL
Masking
TRIPLE
Allocation
RANDOMIZED
Model
CROSSOVER
Primary Purpose
DIAGNOSTIC
Number of Arms
3
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