Repeatability and Concordance of VA Measured With ETDRS Numeric , Landolt C, and Letter Charts in Thai Individuals

Study Overview
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Brief Summary
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This is a cross-sectional study to determine the repeatability and concordance of visual acuity level measured with the original ETDRS letter, ETDRS Landolt C, and ETDRS numeric chart in Thai individuals.

Detailed Description
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The ETDRS visual acuity chart has been used as a standard visual acuity measurement chart in ophthalmic clinical trials due to its proven high repeatability comparing to other visual acuity chart. However, the original ETDRS alphabet chart could not be used in every individual around the world, especially those who are non-english speakers. Landolt C chart has been a recommended chart to test visual acuity in those living in a country where English is not a common language, however, some difficulties including right-left confusion occurred when testing with the Landolt C chart, leading to the unreliable results of visual acuity measurement using the Landolt C chart. Recently, the ETDRS numeric chart was introduced by some medical equipment companies but there is limited information regarding the repeatability and concordance of the new ETDRS numeric chart comparing to the original ETDRS alphabet and Landolt C chart. Therefore, this study aims to determine the repeatability and concordance of visual acuity level measured with the original ETDRS alphabet, the ETDRS Landolt C, and the ETDRS numeric chart. Results from this study would be able to suggest an appropriate ETDRS chart to be used in clinical studies in Thailand or other countries where English is not the native language.

Official Title
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Repeatability and Concordance of Visual Acuity Level Measured With ETDRS Numeric Charts, ETDRS Landolt C Charts, and Original ETDRS Letter Visual Acuity Charts in Thai Individuals

Conditions
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Visual Nonspecific

Intervention / Treatment
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* Behavioral: Visual acuity measurement by ETDRS chart


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Thai nationality More than 18 years of age Educational level: at least high school Able to read English alphabet

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 |
| --- | --- |
| Normal vision group<br>Individuals with VA 20/20 to 20/25 | Behavioral: Visual acuity measurement by ETDRS chart<br>* All participants must complete VA measurement of the study eye using 3 charts including the original ETDRS alphabet, ETDRS Landolt C, and ETDRS numeric charts for 2 times, at least 30 minutes apart.<br>|
| Impaired vision group<br>Individuals with impaired vision: VA of 20/32 to 20/200 due to either cataract, diabetic macular edema, or age-related macular degeneration | Behavioral: Visual acuity measurement by ETDRS chart<br>* All participants must complete VA measurement of the study eye using 3 charts including the original ETDRS alphabet, ETDRS Landolt C, and ETDRS numeric charts for 2 times, at least 30 minutes apart.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Concordance of VA tested with ETDRS alphabet, Landolt C and numeric visual acuity charts |  | Day 1 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Repeatability of VA tested with ETDRS alphabet, Landolt C and numeric visual acuity charts |  | Day 1 | 
| Differences in testing duration of VA measurement across the 3 ETDRS charts |  | Day 1 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Repeatability, Concordance, Agreement, ETDRS visual acuity chart, numeric, Landolt C, Roman alphabet