Reliability of visual orienting response measures in children with and without visual impairments

Background: From the need for a quantitative method to examine visual processing in young children, we measured ocular orienting responses to visual stimuli (form, motion, expansion, color, contrast, cartoons). Reliability and applicability of this method were assessed. New method: 80 children (1-12 years) with visual impairments and a reference group of 118 typically developing children (1-6 years) completed two sessions. Test-retest reliability was measured by calculating differences in reaction time and fixation accuracy between the two sessions. For applicability, the cumulative percentage of children that fell within a pre-defined reliability interval was plotted against the mean number of responses. Results: In typically developing children none of the outcome measures significantly differed between sessions. In the children with visual impairments similar results were obtained, except for motion. This stimulus elicited significantly faster reaction times in the second session. In at least 80% of the children reliable reaction times could be calculated if 4 responses to a cartoon stimulus and 1 or 2 responses to the other stimuli were measured. Comparison with existing method(s): The existing method to quantify visual information processing has been refined: the range of visual functions was extended and a criterion for reliable assessment of orienting response times was established. Conclusions: Objective measurement of orienting responses is a reliable method to test the initial stage of visual processing in children with and without visual impairments. A set minimum number of responses for each stimulus warrants the reliability of measurements obtained with this functional method in clinical practice.

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