Quality Control, Validation Study
Conditions
Keywords
psychophysics, visual acuity, response, response entry, validity, retest reliability, reproducibility, evaluation, optotype, Landolt C
Brief 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.
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.
Interventions
DIAGNOSTIC_TESTLandolt C entry method
Four different methods for entering the Landolt C gap position are compared
Sponsors
Aalen University
Study design
Observational model
COHORT
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
ALL
Age
18 Years to 80 Years
Healthy volunteers
Yes
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| validity | Through study completion, an average of 3 months | Proportion of correct gap position entries in relation to the total number of LC presentations by the four different entry methods |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| retest reliability | Through study completion, an average of 3 months | Comparison of the correct gap position entry between first and second test run by the four different entry methods |
| Examination duration | Through study completion, an average of 3 months | Comparison of the examination duration of the the four different entry methods and by the first and second run |
| Subjects´ satisfaction | Through study completion, an average of 3 months | Subjects´ evaluation (using a questionnaire) for the four different entry methods |
Countries
Germany
Outcome results
None listed