Evaluation of Letters Versus Numbers (ELEVEN) Study

Visual Acuity Clinical Trial

— ELEVEN  

Official title:

Evaluation of Letters Versus Numbers (ELEVEN) Study: ETDRS Visual Acuity Chart Performance in an English Alphabet Illiterate Population

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT04520243
• Other study ID #: ELEVEN
• Status: Completed
• Phase: N/A
• Start date: August 1, 2019
• Est. completion date: January 31, 2020

Study information

• Verified date: August 2020
• Source: The University of Hong Kong
• Contact: n/a
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

This is a prospective randomised controlled trial to determine the performance of Best Corrected Visual Acuity (BCVA) scores using the ETDRS number chart were compared with ETDRS alphabet chart in healthy eyes of patients who do not recognise the English alphabet.

Description:

BACKGROUND: The measurement of visual acuity is important in the clinical setting to assess visual function and treatment response, while in research to provide objective clinical outcomes. The current gold standard for visual acuity measurement in most research studies, including major clinical trials, is the Early Treatment Diabetic Retinopathy Study (ETDRS) chart designed by Bailey and Lovie. However, this may not be suitable for participants who are illiterate. Alternatives exist, including the ETDRS numbers chart, Landolt C chart and Tumbling E chart. Existing studies show that the Landolt C and Tumbling E charts are alternatives with agreement with ETDRS letters chart in healthy and diseased eyes. However, the charts are limited by their 25% (if four orientations) or 12.5% (if eight orientations) chance of guessing the orientation of the letter.

The ETDRS numbers chart may overcome this limitation, as it uses five unique numbers instead of a single rotating letter. There are few studies evaluating the different types of visual acuity measurement among those unfamiliar with the English alphabet. Though one study shows high repeatability and agreement between the ETDRS letters and numbers charts in healthy and diseased eyes of English literate individuals and shorter testing duration when using the numbers chart, this finding has not been validated in individuals unfamiliar with the English alphabet. This study aims to evaluate how the ETDRS letters and numbers charts compare in individuals unfamiliar with the English alphabet.

METHODS: Eligible subjects were divided into 2 groups according to level of literacy. Literacy was determined by self-reported exposure to the English alphabet and recognition of the 10 Sloan letters (C, D, H, K, N, O, R, S, V, and Z). Subjects included were classified into the 2 groups: group A, with no exposure to the English alphabet and recognition of <6/10 letters, and group B, with exposure to the English alphabet and recognition of ≥6/10 letters.

Testing: Each subject underwent 2 rounds of BCVA measurements using 2 types of ETDRS charts in randomized sequence as follows: LN or NL (L = ETDRS letters chart, N = ETDRS numbers chart) from Precision Vision® (PV). The randomization of the testing sequence was performed by a study coordinator independent of study recruiter, optometrist or investigator. Sequentially numbered, opaque and sealed envelopes were used for allocation concealment and opened by the optometrist prior to testing.

The tests were performed and recorded by a single optometrist in the same testing room with similar lighting conditions. For every round of testing, the right eye was examined first, followed by the left eye. For the right eye, numbers chart (PV No. 2702A) and letters chart (PV No. 2173) were used. For the left eye, the numbers chart (PV No. 2714A) and letters chart (PV No. 2174) were used. Different charts (with the same optotypes but in different order) were used for right and left eyes to minimize the effect of learning between consecutive tests.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 59
• Est. completion date: January 31, 2020
• Est. primary completion date: January 31, 2020
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: All
• Age group: 50 Years and older

Eligibility

Inclusion Criteria:

1. Hong Kong residents

2. Age 50 years or above

3. Attending Southern District Screening program

Exclusion Criteria:

1. BCVA 20/200 or below

2. Any clinically relevant ocular disease that might affect visual acuity

Related Conditions & MeSH terms

• Visual Acuity

Intervention

Diagnostic Test:
• Visual acuity assessment by ETDRS charts
All participants must complete VA measurement of both eyes using 2 charts including the ETDRS letters chart and ETDRS numbers chart.

Locations

Country	Name	City	State
Hong Kong	HKSDS Program	Hong Kong

Sponsors (1)

Lead Sponsor	Collaborator
The University of Hong Kong

Country where clinical trial is conducted

Hong Kong, 

References & Publications (10)

Bailey IL, Lovie JE. New design principles for visual acuity letter charts. Am J Optom Physiol Opt. 1976 Nov;53(11):740-5. — View Citation

Chaikitmongkol V, Nanegrungsunk O, Patikulsila D, Ruamviboonsuk P, Bressler NM. Repeatability and Agreement of Visual Acuity Using the ETDRS Number Chart, Landolt C Chart, or ETDRS Alphabet Chart in Eyes With or Without Sight-Threatening Diseases. JAMA Ophthalmol. 2018 Mar 1;136(3):286-290. doi: 10.1001/jamaophthalmol.2017.6290. — View Citation

Doig GS, Simpson F. Randomization and allocation concealment: a practical guide for researchers. J Crit Care. 2005 Jun;20(2):187-91; discussion 191-3. — View Citation

Ferris FL 3rd, Bailey I. Standardizing the measurement of visual acuity for clinical research studies: Guidelines from the Eye Care Technology Forum. Ophthalmology. 1996 Jan;103(1):181-2. — View Citation

Kniestedt C, Stamper RL. Visual acuity and its measurement. Ophthalmol Clin North Am. 2003 Jun;16(2):155-70, v. Review. — View Citation

Koenig S, Tonagel F, Schiefer U, Bach M, Heinrich SP. Assessing visual acuity across five disease types: ETDRS charts are faster with clinical outcome comparable to Landolt Cs. Graefes Arch Clin Exp Ophthalmol. 2014 Jul;252(7):1093-9. doi: 10.1007/s00417-014-2670-y. Epub 2014 May 28. — View Citation

Kuo HK, Kuo MT, Tiong IS, Wu PC, Chen YJ, Chen CH. Visual acuity as measured with Landolt C chart and Early Treatment of Diabetic Retinopathy Study (ETDRS) chart. Graefes Arch Clin Exp Ophthalmol. 2011 Apr;249(4):601-5. doi: 10.1007/s00417-010-1461-3. Epub 2010 Jul 24. — View 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. — View Citation

Treacy MP, Hurst TP, Conway M, Duignan ES, Dimitrov BD, Brennan N, Cassidy L. The early treatment in diabetic retinopathy study chart compared with the tumbling-E and Landolt-C. Ophthalmology. 2015 May;122(5):1062-3.e1. doi: 10.1016/j.ophtha.2014.11.024. Epub 2015 Jan 10. — View Citation

Universal C: Visual Acuity Measurement Standard. Visual Functions Committee 1984.

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	BCVA Measurements	Assessment of BCVA using ETDRS numbers and letters chart and its comparison between the testing groups and intervention methods. All visual acuity tests were performed at 3 metres with at least 15 seconds between each chart. Subjects were asked to read as many optotypes as possible according to the ICO Visual Acuity Measurement Standard.	1 day
Primary	Testing Duration	Assessment of testing duration using ETDRS numbers and letters and its comparison between the testing groups and intervention methods. The testing durations of each visual acuity test were measured and recorded by a single timekeeper with a standard digital chronometer.	1 day