The Test-Retest Reliability of Subjective Visual Horizontal Testing: Comparisons between Solid and Dotted Line Images

The present study aimed to determine the test-retest reliability of subjective visual horizontal (SVH) testing when tested with solid and dotted line images. In this repeated measures study, 36 healthy young Malaysian adults (mean age=23.3±2.3 years, 17 males and 19 females) were enrolled. All of them were healthy and had no hearing, vestibular, balance, or vision problems. The SVH angles were recorded from each participant in an upright body position using a computerized device. They were asked to report their horizontality perception for solid and dotted line images (in the presence of a static black background). After 1 week, the SVH procedure was repeated. The test-retest reliability of SVH was found to be good for both solid line [intraclass correlation (ICC)=0.80] and dotted line (ICC=0.78). As revealed by Bland-Altman plots, for each visual image, the agreements of SVH between the two sessions were within the clinically accepted criteria (±2°). The SVH testing was found to be temporally reliable, which can be clinically beneficial. Both solid and dotted lines in the SVH testing are reliable to be used among young adults.