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

Abstract

PurposeThe aim of the study was to determine the effect of optimal spectral filters on reading performance following stroke. MethodsSeventeen 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. ResultsInitial 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. ConclusionsThe 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.