Clinical trial NCT02810665: Repeatability and Concordance of VA Measured With ETDRS Numeric , Landolt C, and Letter Charts in Thai Individuals
Official title: 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
Study type: OBSERVATIONAL
Overall status: UNKNOWN
Conditions: Visual Nonspecific
Keywords: Repeatability
Concordance
Agreement
ETDRS visual acuity chart
numeric
Landolt C
Roman alphabet
Lead sponsor: Chiang Mai University
Sponsor class: OTHER
First posted: 2016-06-23
Enrollment: 180
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Observational model: CASE_ONLY
Time perspective: CROSS_SECTIONAL
Sampling method: NON_PROBABILITY_SAMPLE
Study population: Participants with normal vision (VA of 20/20 to 20/25) and decreased vision (VA of 20/32 to 20/200 due to cataract, diabetic macular edema, or age-related macular degeneration) who gave consent to participate in this study

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.

Eligibility criteria: Inclusion Criteria:

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

Primary outcomes:
measure: Concordance of VA tested with ETDRS alphabet, Landolt C and numeric visual acuity charts
timeFrame: Day 1
Secondary outcomes:
measure: Repeatability of VA tested with ETDRS alphabet, Landolt C and numeric visual acuity charts
timeFrame: Day 1
measure: Differences in testing duration of VA measurement across the 3 ETDRS charts
timeFrame: Day 1
Other outcomes:
Locations:
city: Muang Chiang Mai
country: Thailand
facility: Voraporn Chaikitmongkol
state: Chiang Mai
Study officials:
References:
citation: Ricci F, Cedrone C, Cerulli L. Standardized measurement of visual acuity. Ophthalmic Epidemiol. 1998 Mar;5(1):41-53. doi: 10.1076/opep.5.1.41.1499.
citation: Ferris FL 3rd, Kassoff A, Bresnick GH, Bailey I. New visual acuity charts for clinical research. Am J Ophthalmol. 1982 Jul;94(1):91-6.
citation: Kaiser PK. Prospective evaluation of visual acuity assessment: a comparison of snellen versus ETDRS charts in clinical practice (An AOS Thesis). Trans Am Ophthalmol Soc. 2009 Dec;107:311-24.
citation: Ruamviboonsuk P, Tiensuwan M, Kunawut C, Masayaanon P. Repeatability of an automated Landolt C test, compared with the early treatment of diabetic retinopathy study (ETDRS) chart testing. Am J Ophthalmol. 2003 Oct;136(4):662-9. doi: 10.1016/s0002-9394(03)00394-5.