Retinal and Choroidal Circulation Changes Following Rapid Ascent to a High Altitude Environment

Study Overview
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Brief Summary
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This is a prospective observational study. The purpose is to explore the effect of high altitude hypobaric hypoxia on retinal microcirculation and the change of the thickness of the retina and choroid by optical coherence tomography angiography (OCTA).

Detailed Description
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Yushu is in Qinghai-Tibet plateau, an average altitude of 4000 m. The medical staff is limited in Yushu. Zhongshan ophthalmic center, sun yat-sen university in Yushu blindness project has lasted many years. Some medical staff who arrived at Yushu will have a plateau response. The high altitude hypoxia on retinal microcirculation evaluated by OCTA has not been reported. The aim of the study is to observe the microcirculation changes after exploring a hypobaric and hypoxia environment using OCTA, and relation with the plateau response. OCTA is a non-invasive examination and could see the microcirculation of the fundus directly and quickly.

Official Title
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Retinal and Choroidal Circulation Changes Following Rapid Ascent to a High Altitude Environment Evaluated by OCT Angiography

Conditions
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High Altitude Retinopathy

Intervention / Treatment
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* Behavioral: High attitude environment


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: The subjects who plan to go to Yushu within one month. Did not live on the high altitude of more than 1000 meters within 6 months. Exclusion Criteria: Unable and unwilling to provide informed consent. Any ocular disease may influence the retinal and choroidal circulation.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 70 Years

Sexes Eligible for Study
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All

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| study group<br>This is a self-control study. Subjects who plan togo to 4000m altitude to work for two weeks will be enrolled. And before and after they arrive high altitude, they will have visual acuity, OCTA, and intraocular pressure; blood pressure, blood oxygen measurement. | Behavioral: High attitude environment<br>* The participants will go to 4000m altitude to work for two weeks.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| retinal microcirculation changes | the vascular density measured by OCTA | 1 month | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Retinal thickness changes | the retinal thickness measured by OCTA | 1 month | 
| Choroidal thickness changes | the subfoveal choroidal thickness measured by OCTA | 1 month | 
| The correlation of retinal microcirculation with the altitude illness | The relationship between retinal vascular density as measured by OCTA and the degree of altitude illness as measured by acute mountain sickness (AMS) scoring system | 1 month | 
| The changes of intraocular pressure | The changes of intraocular pressure measured by icare Tonometer | 1 month | 
| The changes of blood pressure including systolic and diastolic Blood Pressure | The changes of blood pressure measured by Blood Pressure Meter | 1 month | 
| The changes of blood oxygen | The changes of blood Oxygen measured by Pulse Oximeter | 1 month | 
| the degree of altitude illness | the degree of altitude illness was assessed by acute mountain sickness (AMS) scoring system | 1 month |