Multi-center Clinical Trial on Corneal Morphology Analysis in Chinese Population

Study Overview
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Brief Summary
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Based on the corneal morphometry instrumentation Oculus Pentacam, which is commonly used before and after clinical refractive surgery, we will collect the corneal morphological and biologic parameters of the population under refractive surgery screening in refractive surgery centers around the country, and construct corneal morphology database in different living areas of Chinese people. Based on this, compared with the suspected keratoconus and keratoconus population, the screening criteria and reference standards accord with the characteristics of keratoconus of Chinese ethnic will be achieved.

Detailed Description
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The safety of refractive surgery has always been the focus of attention, keratoconus screening is the most important part for the preoperative examination of refractive surgery. Favorable tools and appropriate indicators are the premise of fast and accurate screening, and the corneal morphology from various regions of China have various characteristics, the use of uniform standards developed by foreign screening will always induce a lot of problems, for example, the differences of cornea morphological features between European and American ethnic and Chinese race, as well as the corneal morphometric indicators between various regions of China, will cause varying degrees of false-positive or false-negative screening results. Based on this, in order to further improve the safety of refractive surgery effectively and to obtain the effective and accurate screening of suspected keratoconus population, this study will be conducted to collect the corneal morphological characteristics database of Chinese people from all over the country, and to develop a database of Chinese ethnographic characteristics for screening keratoconus indicators and reference valuable to guide clinical screening and surgical design.

Official Title
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Multi-center Clinical Trial on Corneal Morphology Analysis in Chinese Population

Conditions
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Cornea

Intervention / Treatment
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* Device: Scheimpflug tomography system (Pentacam) measurement


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: No less than 18 years old, in good health, have no active disease in the body and eye, have permanent resident status and have lived in the local area for at least 5 years (please mark the nation). Exclusion Criteria: Eye diseases, glaucoma, ocular hypertension, glaucoma patients with normal pressure, fundus lesions, ptosis and other eyelid abnormalities.

Ages Eligible for Study
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Minimum Age: 18 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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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Chinese population<br>Chinese population of different nation from several provinces. | Device: Scheimpflug tomography system (Pentacam) measurement<br>* The Scheimpflug tomography system (Pentacam,Oculus GmbH, Wetzlar, Germany) is a rotating Scheimpflug camera that measures 138,000 true elevation points to compute corneal topography. Patients were asked to blink twice and then look at the fixation device. Image acquisition was a 2-second scan of 50 rotational Scheimpflug images through the corneal sighting point, the point where the ray of light from the fovea to the fixation device crossed the cornea. All measurements were performed just after a blink to minimize the effect of tear film alteration on the data. Acceptable maps had at least 10.0 mm of corneal coverage with no extrapolated data in the central 9.0 mm zone.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| corneal thickness |  | preoperative | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| corneal curvature measured by the Pentacam system |  | preoperative | 
| coma aberration measured by the Pentacam system |  | preoperative | 
| aspherical index measured by the Pentacam system |  | preoperative | 
| spherical aberration measured by the Pentacam system |  | preoperative | 
| corrected distance visual acuity |  | preoperative | 
| uncorrected distance visual acuity |  | preoperative | 
| refractive diopter |  | preoperative | 
| corneal volume measured by the Pentacam system |  | preoperative | 
| kapple angle measured by the Pentacam system |  | preoperative | 
| introcular pressure |  | preoperative | 
| corneal diameter measured by the Pentacam system |  | preoperative | 
| anterior chamber depth measured by the Pentacam system |  | preoperative | 
| anterior chamber angle measured by the Pentacam system |  | preoperative | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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corneal morphology, Chinese population, corneal curvature, corneal thickness, higher order aberrations