Comparison of Four Methods for Entering the Gap Position of Landolt Cs

Validation Study Clinical Trial

— LC_Entry  

Official title:

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

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT04299659
• Other study ID #: LC Entry_2020
• Status: Completed
• Start date: July 22, 2022
• Est. completion date: June 30, 2023

Study information

• Verified date: July 2023
• Source: Aalen University
• Contact: n/a
• Is FDA regulated: No
• Study type: Observational

Clinical Trial Summary

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.

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.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 24
• Est. completion date: June 30, 2023
• Est. primary completion date: March 1, 2023
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: All
• Age group: 18 Years to 80 Years

Eligibility

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

Related Conditions & MeSH terms

• Quality Control
• Validation Study

Intervention

Diagnostic Test:
• Landolt C entry method
Four different methods for entering the Landolt C gap position are compared

Locations

Country	Name	City	State
Germany	Ulrich SCHIEFER	Aalen	Deutschland

Sponsors (1)

Lead Sponsor	Collaborator
Aalen University

Country where clinical trial is conducted

Germany, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	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	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
Secondary	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
Secondary	Subjects´ satisfaction	Subjects´ evaluation (using a questionnaire) for the four different entry methods	Through study completion, an average of 3 months