NCT03675412 · Wills Eye
Caffeine Consumption in Glaucoma Patients and Healthy Subjects
What this study is about
Caffeine is the most widely consumed drinking nutrient in the world. Caffeine effects various organs and the vascular system. It decreases ocular blood flow due to vasoconstriction.
View original scientific description
Caffeine is the most widely consumed drinking nutrient in the world. Caffeine effects various organs and the vascular system. It decreases ocular blood flow due to vasoconstriction.
Interventions
DIETARY_SUPPLEMENT
Caffeine tablet
Each eligible participant will receive one 200 mg caffeine tablet to ingest after completing all baseline study tasks.
Primary outcome measures
Blood flow change in back of eye before and after caffeine
Time frame: Baseline, Hour 1, Hour 2
Optical Coherence Tomography Angiography (OCTA) will be obtained using the Avanti AngioVue High Definition (HD) OCTA by Optovue. Images will include standard 4.5mm HD disc scan, 6mm HD retina scan, regular optic nerve head (ONH) structural scan, 3D-disc baseline scan and a regular ganglion cell complex analysis (GCCA) structural scan. This will measure blood flow changes in the back of the eye by imaging vessel density in percentage before then 1 and 2 hours after caffeine.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- age 18 to 90 years
- diagnosis of primary open angle glaucoma (Mild, Moderate and Advanced)
- healthy subjects with no eye disease
Exclusion criteria
- Diseases, ophthalmic or systemic, that are likely to affect OCTA results
- greater than moderate cataract
- inability to look at target
- macular degeneration other than mild drusen or pigmentary changes
- diabetic retinopathy
- neovascular glaucoma or non-glaucoma optic neuropathies
- current macular edema, prior laser to retina, inflammatory retinopathy or choroidopathy
- keratoconus, corneal ectasia, central corneal scarring
- rheumatologic diseases or Raynaud's phenomena
- pregnant and lactating women
- mental illness or alcohol addiction
- pre-existing bladder symptoms, cardiac disease or sleep disorder
- refractive spherical diopter greater than 5 or cylinder greater than 3
- possible tolerance to caffeine (drinking more than 1 cup coffee per day).
Where
- Philadelphia, Pennsylvania
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Nov 14, 2025 · Source of record for eligibility and locations