The Effects of Caffeinated Coffee on Intraocular Pressure

Study Overview
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Brief Summary
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High intraocular pressure (IOP) is a known risk factor for developing primary open-angle glaucoma (POAG). There is controversy in the literature regarding the degree to which caffeine influences IOP, with some studies reporting minimal changes in IOP while others report up to 4 mmHg increases. To date there are no double-masked randomized controlled trials that examine acute caffeinated coffee's effects on IOP in patients with or at risk for primary open-angle glaucoma. The investigators aim to better understand the relationship between acute caffeinated coffee (vs decaffeinate coffee) consumption and IOP in a double-masked, crossover randomized controlled clinical trial.

Official Title
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The Effects of Caffeinated Coffee on Intraocular Pressure

Conditions
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Primary Open Angle Glaucoma

Intervention / Treatment
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* Other: Caffeinated Coffee
* Other: Decaffeinated Coffee


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 40-89 yrs POAG for cases or no forms of glaucoma for controls Willingness to drink coffee Consent signed Exclusion Criteria: Age less than 40 or greater than 89 yrs all forms of glaucoma other than POAG any condition inappropriate for tonometry (ie corneal disease, LASIK) unable or unwilling to give consent unable or unwilling to drink coffee pregnancy

Ages Eligible for Study
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Minimum Age: 40 Years
Maximum Age: 89 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Caffeinated Coffee 1st Visit, Decaffeinated Coffee 2nd Visit<br>Participants will be given an 8 oz cup of caffeinated coffee on their first visit and 8 oz cup of decaffeinated coffee on their second visit. | Other: Caffeinated Coffee<br>* Participants will drink one 8 oz cup in the morning hours. Participants have 15 minutes to drink the coffee but may do so in less time.<br>Other: Decaffeinated Coffee<br>* Participants will drink one 8 oz cup in the morning hours. Participants have 15 minutes to drink the coffee but may do so in less time.<br>|
| Experimental: Decaffeinated Coffee 1st Visit, Caffeinated Coffee 2nd Visit<br>Participants will be given an 8 oz cup of decaffeinated coffee on their first visit and 8 oz cup of caffeinated coffee on their second visit. | Other: Caffeinated Coffee<br>* Participants will drink one 8 oz cup in the morning hours. Participants have 15 minutes to drink the coffee but may do so in less time.<br>Other: Decaffeinated Coffee<br>* Participants will drink one 8 oz cup in the morning hours. Participants have 15 minutes to drink the coffee but may do so in less time.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Intraocular Pressure at 60 Minutes | At the caffeinated coffee visit: Change in intraocular pressure at 60 minutes = intraocular pressure at 60 minutes post caffeinated coffee ingestion minus intraocular pressure at baseline prior to caffeinated coffee ingestion At the decaffeinated coffee visit: Change in intraocular pressure at 60 minutes = intraocular pressure at 60 minutes post decaffeinated coffee ingestion minus intraocular pressure at baseline prior to decaffeinated coffee ingestion | Prior to coffee ingestion (baseline), 60 minutes post coffee ingestion | 
| Change in Intraocular Pressure at 90 Minutes | At the caffeinated coffee visit: Change in intraocular pressure at 90 minutes = intraocular pressure at 90 minutes post caffeinated coffee ingestion minus intraocular pressure at baseline prior to caffeinated coffee ingestion At the decaffeinated coffee visit: Change in intraocular pressure at 90 minutes = intraocular pressure at 90 minutes post decaffeinated coffee ingestion minus intraocular pressure at baseline prior to decaffeinated coffee ingestion | Prior to coffee ingestion (baseline), 90 minutes post coffee ingestion |