The goal of this study is to understand how caffeine and alcohol affect the ocular and physiological systems, especially how the pupil (the aperture in the colored part of the eye) responds to light. It will also test whether these changes can be used to detect recent caffeine or alcohol intake using a portable eye device. The main questions it aims to answer are: 1. How does caffeine change pupil responses, eye movements, and other ocular and physiological measurements? 2. How does alcohol change these same ocular and physiological responses? 3. Are the effects of caffeine and alcohol different from each other? 4. Can these changes be used to accurately identify whether someone has consumed caffeine or alcohol? Researchers will compare caffeine, alcohol, and a placebo (a look-alike drink with no active substance) to see how each affects the ocular and physiological outcomes. Participants will: 1. Attend three separate sessions where they will consume caffeine, alcohol, or a placebo (in random order) 2. Undergo pupillary response evaluation using a handheld device that measures responses to different colored light stimuli 3. Have their eye movements analyzed 4. Have retinal and choroidal thickness, blood perfusion, and ocular oxygen levels measured 5. Have basic body measurements recorded (such as pulse rate and blood pressure) 6. Complete tests at multiple time points over 2 hours after consumption The results of this study may help develop a quick and non-invasive way to detect recent caffeine or alcohol use for clinical and safety purposes.
Age range
30 Years – 50 Years
Sex
ALL
See this in plain English?
AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.
Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.
Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.
The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.
A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.
Baseline Pupil Size
Timeframe: Baseline (pre-intervention), 30, 60, 90, and 120 minutes post-intervention - during each of the 3 study visits (up to 3 study days total)
Phasic Pupil Constriction to Blue Light
Timeframe: Baseline (pre-intervention), 30, 60, 90, and 120 minutes post-intervention - during each of the 3 study visits (up to 3 study days total)
Maximum Pupil Constriction to Blue Light
Timeframe: Baseline (pre-intervention), 30, 60, 90, and 120 minutes post-intervention - during each of the 3 study visits (up to 3 study days total)
Pupil Constriction Latency to Blue Light
Timeframe: Baseline (pre-intervention), 30, 60, 90, and 120 minutes post-intervention - during each of the 3 study visits (up to 3 study days total)
Phasic Pupil Constriction to Red Light
Timeframe: Baseline (pre-intervention), 30, 60, 90, and 120 minutes post-intervention - during each of the 3 study visits (up to 3 study days total)
Maximum Pupil Constriction to Red Light
Timeframe: Baseline (pre-intervention), 30, 60, 90, and 120 minutes post-intervention - during each of the 3 study visits (up to 3 study days total)
Pupil Constriction Latency to Red Light
Timeframe: Baseline (pre-intervention), 30, 60, 90, and 120 minutes post-intervention - during each of the 3 study visits (up to 3 study days total)
Phasic Pupil Constriction to Continuous White Light
Timeframe: Baseline (pre-intervention), 30, 60, 90, and 120 minutes post-intervention - during each of the 3 study visits (up to 3 study days total)
Maximum Pupil Constriction to Continuous White Light
Timeframe: Baseline (pre-intervention), 30, 60, 90, and 120 minutes post-intervention - during each of the 3 study visits (up to 3 study days total)
Pupil Constriction Latency to Continuous White Light
Timeframe: Baseline (pre-intervention), 30, 60, 90, and 120 minutes post-intervention - during each of the 3 study visits (up to 3 study days total)
Maximum Pupil Constriction to White Light Flash
Timeframe: Baseline (pre-intervention), 30, 60, 90, and 120 minutes post-intervention - during each of the 3 study visits (up to 3 study days total)
Post-Stimulus Pupil Recovery Slope to Blue Light
Timeframe: Baseline (pre-intervention), 30, 60, 90, and 120 minutes post-intervention - during each of the 3 study visits (up to 3 study days total)
Pupil Slope to Blue Light 1.7s before Blue Light Offset
Timeframe: Baseline (pre-intervention), 30, 60, 90, and 120 minutes post-intervention - during each of the 3 study visits (up to 3 study days total)
Pupil Slope to Blue Light 1.7s after Blue Light Offset
Timeframe: Baseline (pre-intervention), 30, 60, 90, and 120 minutes post-intervention - during each of the 3 study visits (up to 3 study days total)
Post-Stimulus Pupil Recovery Slope to Red Light
Timeframe: Baseline (pre-intervention), 30, 60, 90, and 120 minutes post-intervention - during each of the 3 study visits (up to 3 study days total)
Post-Stimulus Pupil Recovery Slope to White Light Flash
Timeframe: Baseline (pre-intervention), 30, 60, 90, and 120 minutes post-intervention - during each of the 3 study visits (up to 3 study days total)
Post-Stimulus Pupil Recovery Slope to Continuous White Light
Timeframe: Baseline (pre-intervention), 30, 60, 90, and 120 minutes post-intervention - during each of the 3 study visits (up to 3 study days total)
PIPR at 6 s - Blue Light
Timeframe: Baseline (pre-intervention), 30, 60, 90, and 120 minutes post-intervention - during each of the 3 study visits (up to 3 study days total)
PIPR at 12 s - Blue Light
Timeframe: Baseline (pre-intervention), 30, 60, 90, and 120 minutes post-intervention - during each of the 3 study visits (up to 3 study days total)
PIPR Area Under the Curve (0-12 s) - Blue Light
Timeframe: Baseline (pre-intervention), 30, 60, 90, and 120 minutes post-intervention - during each of the 3 study visits (up to 3 study days total)
PIPR at 6 s - Red Light
Timeframe: Baseline (pre-intervention), 30, 60, 90, and 120 minutes post-intervention - during each of the 3 study visits (up to 3 study days total)
PIPR Area Under the Curve - Red Light
Timeframe: Baseline (pre-intervention), 30, 60, 90, and 120 minutes post-intervention - during each of the 3 study visits (up to 3 study days total)
PIPR at 6 s - Flash White Light
Timeframe: Baseline (pre-intervention), 30, 60, 90, and 120 minutes post-intervention - during each of the 3 study visits (up to 3 study days total)
PIPR at 6 s - Continuous White Light
Timeframe: Baseline (pre-intervention), 30, 60, 90, and 120 minutes post-intervention - during each of the 3 study visits (up to 3 study days total)