The effect of spectral filters on reading speed and accuracy following stroke

Abstract

Purpose: The aim of the study was to determine the effect of optimal spectral filters on reading performance following stroke. Methods: Seventeen stroke subjects, aged 43–85, were considered with an age-matched Control Group (n = 17). Subjects undertook the Wilkins Rate of Reading Test on three occasions: (i) using an optimally selected spectral filter; (ii) subjects were randomly assigned to two groups: Group 1 used an optimal filter, whereas Group 2 used a grey filter, for two-weeks. The grey filter had similar photopic reflectance to the optimal filters, intended as a surrogate for a placebo; (iii) the groups were crossed over with Group 1 using a grey filter and Group 2 given an optimal filter, for two weeks, before undertaking the task once more. An increase in reading speed of >5% was considered clinically relevant. Results: Initial use of a spectral filter in the stroke cohort, increased reading speed by ∼8%, almost halving error scores, findings not replicated in controls. Prolonged use of an optimal spectral filter increased reading speed by >9% for stroke subjects; errors more than halved. When the same subjects switched to using a grey filter, reading speed reduced by ∼4%. A second group of stroke subjects used a grey filter first; reading speed decreased by ∼3% but increased by ∼4% with an optimal filter, with error scores almost halving. Conclusions: The present study has shown that spectral filters can immediately improve reading speed and accuracy following stroke, whereas prolonged use does not increase these benefits significantly.

Keywords

• Stroke
• Visual rehabilitation
• Spectral filters
• Cortical hyperexcitability
• Pattern glare