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

Chiang Mai University

Status: Unknown

Conditions: Visual Nonspecific

Treatments: Behavioral: Visual acuity measurement by ETDRS chart

Study type: Observational

Funder types: Other

Identifiers

NCT02810665

OPT-2558-03133

Details and patient eligibility

About

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.

Full 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.

Enrollment: 180 estimated patients

Sex: All

Ages: 18+ years old

Volunteers: Accepts Healthy Volunteers

Inclusion and exclusion criteria

Inclusion Criteria:

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

Trial design

180 participants in 2 patient groups

Normal vision group

Description:

Individuals with VA 20/20 to 20/25

Treatment:

Behavioral: Visual acuity measurement by ETDRS chart

Impaired vision group

Description:

Individuals with impaired vision: VA of 20/32 to 20/200 due to either cataract, diabetic macular edema, or age-related macular degeneration

Treatment:

Behavioral: Visual acuity measurement by ETDRS chart