Reliability of visual temporal thresholds

Visual processing deficits involving temporal characteristics are typically not captured by the widely used outcome measures (i.e., Expanded Disability Status Scale, Multiple Sclerosis Functional Composite) in multiple sclerosis (MS). Visual temporal thresholds (i.e., measurements of the temporal aspects in visual processing) are typically significantly higher (i.e., prolonged) in MS patients when compared to controls. The test-retest reliability of these thresholds was examined in patients with MS.

Visual temporal thresholds were measured in 21 stable MS patients during two separate test sessions. Test-retest reliability and the standard error of measurement were calculated. The threshold of change in visual temporal thresholds in MS patients that would correspond to real change beyond measurement error with 95% certainty was also calculated. For comparisons, a control group (n = 10) was included.

The test-retest reliability of this measure of visual temporal thresholds was 0.97. The threshold indicating change beyond chance or measurement error with 95% certainty was 11 ms. Higher thresholds were significantly correlated with longer durations of disease.

This measure of visual temporal thresholds has excellent test-retest reliability and a change of greater than 11 ms is highly likely to represent real change in MS patients. The findings indicate that these measurements may provide useful clinical information about functional changes regarding the temporal aspects of the visual system, which is currently not captured by the Extended Disability Status Scale.