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.