External Influences Upon Ocular Homeostasis

Study Overview
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Brief Summary
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Our experiments are designed to test the overall hypothesis that position-dependent or water-dependent intra-ocular pressure (IOP) spikes occur in humans, and that these challenge ocular homeostasis.

Detailed Description
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Glaucoma is the second leading cause of blindness in the United States, yet its pathogenesis is poorly understood. This is an insidious disorder since the loss of peripheral vision which occurs first usually is not noticed by the victim. Approximately 1 million people in the United States have glaucoma, but are not aware of it. Glaucoma is not always associated with elevated intraocular pressures so that vision screenings which measure just intraocular pressure without assessing the optic nerve will also miss these patients with glaucomatous damage. Therefore, patients are often diagnosed only when they have severe irreversible vision loss. Vascular insufficiency or abnormal autoregulation versus mechanical pressure damage has been proposed as a major factor in the development of glaucoma. Presently, therapy is based upon lowering intraocular pressure. If a contributing intermittent pressure elevation factor can be elucidated and characterized, specific treatment modalities may then be developed and their effectiveness can be monitored.

Official Title
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External Influences Upon Ocular Homeostasis

Conditions
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Intraocular Pressure

Intervention / Treatment
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* Behavioral: Postural change
* Behavioral: Water drinking


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients with autonomic dysfunction Patients with open-angle glaucoma Patients with normal-pressure glaucoma Normal subjects Exclusion criteria: Medical students Prisoners Pregnant women

Ages Eligible for Study
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Minimum Age: 10 Years
Maximum Age: 90 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

Primary Purpose: Basic Science
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Subjects with autonomic dysfunction<br>Subjects with known autonomic dysfunction diagnoses as defined by the General Clinical Research Center (GCRC) such as pure autonomic failure, Postural orthostatic tachycardia syndrome (POTS), and Multiple System Atrophy( MSA). Intraocular pressures, blood pressures, and retinal thicknesses are measured with postural changes Intraocular pressures, blood pressures, and retinal thicknesses are measured with water drinking. | Behavioral: Postural change<br>* Intraocular pressures, blood pressures, and retinal thicknesses are measured with postural changes<br>Behavioral: Water drinking<br>* Intraocular pressures, blood pressures, and retinal thicknesses are measured with water drinking.<br>|
| Experimental: Primary open-angle glaucoma subjects<br>Subjects diagnosed with primary open-angle glaucoma following a glaucoma specialist's examination. Intraocular pressures, blood pressures, and retinal thicknesses are measured with postural changes Intraocular pressures, blood pressures, and retinal thicknesses are measured with water drinking. | Behavioral: Postural change<br>* Intraocular pressures, blood pressures, and retinal thicknesses are measured with postural changes<br>Behavioral: Water drinking<br>* Intraocular pressures, blood pressures, and retinal thicknesses are measured with water drinking.<br>|
| Experimental: Subjects with normal-pressure glaucoma<br>Subjects with open-angle glaucoma damage following a glaucoma specialist's examination without ever an intraocular pressure recording greater than 21 mm Hg. .1. Intraocular pressures, blood pressures, and retinal thicknesses are measured with postural changes 2. Intraocular pressures, blood pressures, and retinal thicknesses are measured with water drinking. | Behavioral: Postural change<br>* Intraocular pressures, blood pressures, and retinal thicknesses are measured with postural changes<br>Behavioral: Water drinking<br>* Intraocular pressures, blood pressures, and retinal thicknesses are measured with water drinking.<br>|
| Active Comparator: Normal subjects<br>Subjects without evidence of glaucoma or autonomic dysfunction. ..1. Intraocular pressures, blood pressures, and retinal thicknesses are measured with postural changes 2. Intraocular pressures, blood pressures, and retinal thicknesses are measured with water drinking. | Behavioral: Postural change<br>* Intraocular pressures, blood pressures, and retinal thicknesses are measured with postural changes<br>Behavioral: Water drinking<br>* Intraocular pressures, blood pressures, and retinal thicknesses are measured with water drinking.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Intraocular Pressure | A change in intraocular pressure is measured after change in posture or drinking water. | Within 1 day | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Intraocular Pressure