Improving Crowding in Dyslexic Children by Visual Training: Conflicting Results from a Single-masked Crossover Pilot Study.

Aims: To evaluate the effectiveness of visual training aimed at reducing crowding in dyslexic children. Study Design: Single-masked crossover pilot study. Place and Duration of Study: University of Turin and the Gradenigo Hospital, Department of Ophthalmology, Turin, between January and November 2013. Methodology: 15 dyslexic children underwent a visual training devised to reduce crowding. Patients were asked to recognize trigrams of letters with different spacing displayed at different eccentricities on both sides of the fixation point. As a placebo half of the sample was administered a contrast sensitivity test. Average reading rate for words and non-words with different interletter spacing was measured before and after the visual training and the placebo. The sample was divided into two subgroup: G1, who was first administered the training, and G2, who underwent first the placebo trial. Results: After the training in G1 reading rate for words increased from 1.54 syl/sec (±0.60) to 1.74 syl/sec (± 0.64) (P= .001). Reading rate for non-words improved from 0.94 (0.68-1.55) syl/sec to 1.03 (0.85-1.63) syl/sec. No significant improvement was found after the administration of the placebo (T2) when testing words and non-words Analysis of variance showed a significant placebo x treatment effect for words (P= .001) and a barely significant effect for non-words (P= .05). In G2 no significant improvement was found after the placebo both at words and non-words (from 1.69 syl/sec [±0.83] to 2.01 syl/sec [±0.94] for words, from 1.07 syl/sec [±0.51] to 1.08 syl/sec [±0.50] for nonwords). In this group the training increased the reading rate for words and non-words (from 2.01 syl/sec to 2.12 syl/sec [±1.13]; non-words: from 1.08 syl/sec to 1.22 syl/sec [±0.59]). However, analysis of variance did not show a significant effect of the treatment (words: P= .70; non-words: P= .85). Conclusion: Factors other than visuoperceptive, in particular the phonological impairment, could help to account for the controversial results obtained in the small group of dyslexic children recruited in this study. In future investigations, performed on a larger sample, a classification aimed at ruling out patients mainly affected by phonological defects should be considered, in order to select the appropriate target suitable for such kind of approach.

Domitest-S: A Novel Dichoptic Technique to Assess Ocular Sensory Dominance in Children: A Population Study.

Aims: To assess sensory ocular dominance of children by means of a novel psychophysical technique (Domitest-S). Study Design: population study. Place and Duration of Study: Department of Ophthalmology, The Gradenigo Hospital, Turin, between June 2012 and June 2013. Methodology: Thirty sequences of stimuli (15 for the left eye and 15 for the right eye) were administered in dichoptic conditions to 152 pupils (mean age: 9 ± .8 years). The task was to detect the target (a checkerboard-like pattern arranged so as to form an “X”) embedded in a series of null stimuli (checkerboard-like patterns randomly arranged). Left and right proportion correct responses were computed and an index of dominance laterality, the Balance Value (BV), expressed as the right minus left proportion correct responses was introduced. A second index based on the total amount of percent correct responses, the Interocular Inhibitory Index (III) was computed to provide a measure of reciprocal binocular suppression. Results: The frequency distribution of sensory dominance was not normal, but skewed on the left (KS=.17, P<.001). The median was .20 (range .00-.80) with 77% of the subjects showing a BV between .00 and .27. A substantial equivalence was found between the proportion of right and left dominants (46%). Balance values ranging from – .20 to +.27 accounted for 79% of the variance. The distribution of the reciprocal interocular suppression measured as III was bimodal, showing two peaks, one on the right (lower inter-inhibitory effect) and the other on the left (stronger inter-inhibitory effect). Test-retest reliability was acceptable (correlation between the left and right correct responses at first and second examination: Spearman r= .54, P< .001). The duration of the examination was about 5 minutes. Conclusion: Domitest-S proves to be a fast and reliable technique to assess sensory dominance in children within the clinical setting.