The authors wished to determine the current practice of assessing and interpreting the density of suppression with the Sbisa / Bagolini filter bar in the management of amblyopia in the UK and to estimate the incidence of intractable diplopia following amblyopia treatment. Their questionnaire survey had a response rate of 54%. Testing and test conditions reported the minimum age for assessing density of suppression to be a mean of 5.9±1.1 years. Assessment was conducted in normal background illumination by 91% of respondents. Potential binocular vision assessment was undertaken by 61% with prisms or using the synoptophore. Interpretation questions showed considerable variation with a median choice of filter 8. Decisions were based on clinical judgment, clinical experience of previous cases of intractable diplopia and a combination. Only 3% of decisions were evidence-based. There was a small significant reduction in time between visits if risk of intractable diplopia was being assessed: mean of 7.1±1.5 versus 6.1±1.8 weeks. If starting to notice diplopia, there was a significant increase in the proportion of orthoptists that would reduce the amount of treatment. For intractable diplopia, 91% had never seen a case in the last five years. The authors conclude there is a great deal of uncertainty as to the age at which density of suppression should be monitored, how the Sbisa results should be interpreted and actions to take when density of suppression reduces.

Assessment of the density of suppression to identify risk of intractable diplopia in the UK.
Newsham D, O’Connor AR.
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Fiona Rowe (Prof)

Institute of Population Health, University of Liverpool, UK.

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