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

• Conditions: Visual Nonspecific
• Interventions: Behavioral: Visual acuity measurement by ETDRS chart

• Registration Number: NCT02810665
• Lead Sponsor: Chiang Mai University

Brief Summary

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

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.

Study Timeline

• Study Start: 2015-07
• Status Verified: 2016-06
• Study First Submitted: 2016-06-16
• Study First Submitted QC: 2016-06-20
• Last Update Submitted: 2016-06-20
• Study First Posted: 2016-06-23
• Last Update Posted: 2016-06-23
• Primary Completion: 2016-07
• Study Completion: 2016-07

Recruitment & Eligibility

• Status: UNKNOWN
• Sex: All
• Target Recruitment: 180

Inclusion Criteria

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

Exclusion Criteria

Not provided

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Arm && Interventions

Group	Intervention	Description
Impaired vision group	Visual acuity measurement by ETDRS chart	Individuals with impaired vision: VA of 20/32 to 20/200 due to either cataract, diabetic macular edema, or age-related macular degeneration
Normal vision group	Visual acuity measurement by ETDRS chart	Individuals with VA 20/20 to 20/25

Primary Outcome Measures

Name	Time	Method
Concordance of VA tested with ETDRS alphabet, Landolt C and numeric visual acuity charts	Day 1

Secondary Outcome Measures

Name	Time	Method
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

Trial Locations

Locations (1)

Voraporn Chaikitmongkol; 🇹🇭 Muang Chiang Mai, Chiang Mai, Thailand