Reliability of Pachymetry Measurement With FD-oCT, ORA, Confoscan 4 and Ultrasound

Study Overview
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Brief Summary
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The purpose of this study is to assess the repeatability, reproducibility, and agreement of central corneal thickness measured by Fourier Domain Optical Coherence tomography (FD-OCT, OptoVue, USA) with anterior corneal module, 20MHz ultrasound pachymetry equipped with Ocular response analyzer (ORA, Reichert Ophthalmic Instruments, USA) and 10MHz Ultrasound Pachymetry (USP).

Detailed Description
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Corneal thickness measurements are clinically important. Variation in corneal thickness affects the accuracy of applanation tonometry. A meta-analysis by Doughty and Zaman showed that a 10% change in central corneal thickness may result in an approximately 3.4-mmHg change in intraocular pressure.1 Accuracy of corneal thickness measurement is also important in considering eligibility for refractive surgery, and the amount of correction that can safely be performed. Underestimation of corneal thickness may lead to eligible patients being excluded for primary or enhancement refractive procedures. Overestimation may lead to over-ablation and inadvertent thinning of the stroma, thereby increasing the risk of iatrogenic keratectasia. Hence, studies assessing corneal thickness measurements by various instruments are of high clinical relevance.2-9 Fourier domain optical coherence tomography (FD-OCT, OptoVue, U.S.A), Confoscan 4 (CS-4, Nidek, USA) and ocular response analyzer (ORA, Reichert, USA) are non-invasive medical devices that have recently received FDA approval for measurement of the cornea thickness. However, the repeatability and reproducibility of these instruments remains unproven in the clinical settings. To our knowledge, this is the first study to describe agreement, repeatability and reproducibility in corneal pachymetric mapping between FD-OCT, ORA, CS-4 and conventional ultrasound (US), which has been the current reference corneal pachymetric mapping system for the majority of refractive surgeons.

Official Title
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Repeatability and Reproducibility of Pachymetric Mapping With Fourier Domain Optical Coherence Tomography, Ocular Response Analyzer, Confoscan 4 and Ultrasound

Conditions
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Keratitis

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy Volunteers Exclusion Criteria: Patients who had history of prior ocular surgery, ocular abnormalities other than cataract or refractive error or were unable to cooperate in the examination were excluded.

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 70 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 |
| --- | --- |
| FD-OCT, ORA, USP<br> | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Repeatability and reproducibility of corneal thickness measurement |  | 3 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Comparing central corneal thickness measurement among FD-OCT, ORA, and USP |  | 3 months |