What is this study trying to find out about caffeine and alcohol effects on the eye?

This study is investigating how caffeine and alcohol impact pupil responses, eye movements, and other eye and body functions. Researchers want to see if these changes can help detect recent use of these substances. The National University of Singapore is leading this research to improve non-invasive screening methods.

Who may be eligible for this caffeine and alcohol clinical trial?

Adults aged 30 to 50 years who have good vision and are willing to consume caffeine and alcohol may be eligible. Participants must not have certain eye or neurological diseases, not be pregnant or breastfeeding, and avoid medications affecting alertness. Please review eligibility criteria for more details.

Is there any cost to participate in this caffeine and alcohol clinical trial?

Study-related care, including the study tablets, beverages, and all trial visits, is provided at no cost. Personal travel expenses may vary and are not guaranteed to be covered.

Actively Recruiting

Phase Not Applicable

Age: 30Years - 50Years

All Genders

Healthy Volunteers

ID07625358

Study on How Caffeine and Alcohol Affect Pupil Responses and Eye Function Using a Portable Eye Device for Detection

Led by National University of Singapore · Updated on 2026-06-04

100

Participants Needed

Research Sites

26 weeks

Total Duration

AI-Summary

What this Trial Is About

Researchers are studying how caffeine and alcohol affect the eyes 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 mgkg, 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

Age: 30Years - 50Years

All Genders

Healthy Volunteers

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)

Your Study Journey

Screening

Duration - 2 to 4 weeks

Participants are screened for eligibility to participate in the trial.

1 visit (in-person)

Treatment

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)

Monitoring

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