The repeatability of the Sbisa bar for testing density of suppression

Laura Crawford, Helen Griffiths


Aim: The density of suppression is often assessed in children undergoing amblyopia treatment. The pur- pose of this study was to assess the repeatability of the Sbisa bar to measure density of suppression by the same and different observers.

Methods: A prospective repeated measures study was performed on participants aged 5–16 years. Partici- pants with constant suppression due to strabismus had the Sbisa bar test performed twice by one observer and once by a second observer with a period of 15 minutes between each test.

Results: Thirty participants were recruited with a mean age 7.3 years (range 5.1–15.1 years). Median filter value for the first test was 15 (interquartile range (IQR) 14–17), for the second test was 15 (IQR 13–17) and for the third test was 14 (IQR 13–17). Interclass correlation coefficient was 0.70 (95% CI 0.46 to 0.85) for the same observer and 0.73 (95% CI 0.44 to 0.87) for different observers. Inter-rater repeatability coefficient, k, was 0.32, SE 0.11 (95% CI 0.10 to 0.54). There was no correlation between the median filter value from the first observer’s tests with age (R = 0.08), visual acuity in the amblyopic eye (R = 0.01) or visual acuity difference (R = 0.01). Conclusions: The results show that in patients with suppression > filter 10 the Sbisa bar is repeatable within one to three filters when assessed by the same or different observers. There is no correlation between density of suppression and visual acuity or age.



Bagolini filter bar;Repeatability;Sbisa bar;Suppression

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Copyright (c) 2016 Laura Crawford, Helen Griffiths

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