Comparison of Four Methods for Entering the Gap Position of Landolt Cs (LC_Entry)

Comparison of Four Methods for Entering the Gap Position of Landolt Cs With Respect to Validity, Retest Reliability, Examination Duration and Test Subject Satisfaction

The aim of this study is to investigate and compare the validity of four different input methods for Landolt Cs, i.e. the proportion of correct gap positions in relation to the total number of performances. The four input methods are a numeric keypad, an eight-positions rocker switch, a remote control and voice feedback.

Study Overview

• Status: Completed
• Conditions: Validation Study; Quality Control
• Intervention / Treatment: Diagnostic test: Landolt C entry method

Detailed Description

The measurement of visual acuity is the most frequent and one of the most important ophthalmological functional investigations. Therefore, it is particularly important to find a measuring procedure with as little input errors as possible.

The 8-position Landolt C (LC) is the internationally accepted, well-standardised optotype for the determination of visual acuity.

Usually, the subjects informs the examiner verbally about the perceived position of each LC. According to the current literature, about 20 to 30 % of the population suffers from a right/left weakness. Furthermore, language barriers are an additional considerable hurdle.

Therefore, it is important to find an input method for the LC gap positions with minimal entry mistakes. In oder to avoid the thresholding procedure and its inherent difficulties, highly supra-threshold (10 times above the previously determined individual central visual acuity threshold) 8-position LCs are presented.

The study compares four input methods for entering of the Landolt C gap positions: a modified numeric keypad, an 8-position rocker switch, a modified TV remote control and voice/verbal feedback.

Each subject will perform all four input methods, with 2 test runs of 16 Landolt C presentations, each. A forced-choice method will be applied, i.e. the test is not continued until the test person has responded ot each single presentation. Regardless of whether the entry was correct or incorrect, the next Landolt C is displayed.

The optotypes are presented using modified version of the Freiburg Visual Acuity and Contrast Test (FrACT), which allows to present the 8-position Landolt Cs in a standardized way on a video display unit (VDU).

The sequence of the input methods is randomized. This study is carried out in a "within-subject design", i.e. all test persons go through all test conditions and serve as their own controls.

• Study Type: Observational
• Enrollment (Actual): 24

Contacts and Locations

Study Locations

• Germany
  • Deutschland
    • Aalen, Deutschland, Germany, 73430
      • Ulrich SCHIEFER

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 14 years to 76 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

Healthy, young subjects recruited for the students and or co-workers of the Aalen University of Applied Sciences

Description

Inclusion Criteria:

• Age: ≥ 18 years
• Informed consent
• (Distance) visual acuity with best correction: ≥ 0.8
• (Distant) ametropia: ≤+8.0 Diopters (spherical equivalent)
• Anisometropia ≤ 3 dpt
• Astigmatism ≤ 2.5 dpt

Exclusion Criteria:

• Prolonged reaction time caused by drugs (medications)/ drugs/alcohol
• Movement disorders (of hands) such as Parkinson's disease
• Indication of amblyopia (strabismus surgery, occlusion therapy etc.)
• Eye movement disorders/double vision
• Defective stereo vision (according to LANG [I] stereo test)
• Presence of a relative afferent pupil defect ("swinging flashlight test)
• Any hint of visual pathway lesion or other chronic or progressive eye disease

Study Plan

How is the study designed?

Design Details

• Observational Models: Cohort
• Time Perspectives: Prospective

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
validity	Proportion of correct gap position entries in relation to the total number of LC presentations by the four different entry methods	Through study completion, an average of 3 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
retest reliability	Comparison of the correct gap position entry between first and second test run by the four different entry methods	Through study completion, an average of 3 months
Examination duration	Comparison of the examination duration of the the four different entry methods and by the first and second run	Through study completion, an average of 3 months
Subjects´ satisfaction	Subjects´ evaluation (using a questionnaire) for the four different entry methods	Through study completion, an average of 3 months

Collaborators and Investigators

• Sponsor: Aalen University
• Investigators: Study Chair: Ulrich Schiefer, M.D., +49 7361 576-4605

Study record dates

Study Major Dates

• Study Start (Actual): July 22, 2022
• Primary Completion (Actual): March 1, 2023
• Study Completion (Actual): June 30, 2023

Study Registration Dates

• First Submitted: March 1, 2020
• First Submitted That Met QC Criteria: March 6, 2020
• First Posted (Actual): March 9, 2020

Study Record Updates

• Last Update Posted (Actual): July 20, 2023
• Last Update Submitted That Met QC Criteria: July 19, 2023
• Last Verified: July 1, 2023

More Information

Terms related to this study

• Keywords: response; validity; evaluation; visual acuity; reproducibility; psychophysics; response entry; retest reliability; optotype; Landolt C
• Other Study ID Numbers: LC Entry_2020

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No