Ophthalmic Physiol Opt. 2002 Nov;22(6):535-45.
The effect of coloured filters on the rate of reading in an adult student
population.
Evans BJ, Joseph F.
Institute of Optometry, Newington Causeway, London, UK. bruce.evans@virgin.net
Meares-Irlen Syndrome is characterised by visual stress (visual discomfort) and
visual perceptual distortions that can be alleviated by individually prescribed
coloured filters. The benefit from coloured filters can be demonstrated with the
Wilkins Rate of Reading Test (WRRT). Previous research using individually
prescribed coloured overlays (sheets of plastic placed on a page) found that
between one-fifth and one-third of unselected school-children show a significant
(> 5%) improvement in their rate of reading with their chosen overlay. This 5%
cut-off has good sensitivity and specificity for predicting those children who
will continue to voluntarily use their overlay for a sustained period. Previous
research has concentrated on children, and we sought to investigate the
immediate effect of overlays on rate of reading in an adult population. Subjects
were 113 unselected university students who answered a symptom questionnaire and
were tested with the Wilkins Intuitive Overlays and WRRT. Some symptoms were
common: 73% reported sore or tired eyes when reading and 40% reported four to 12
headaches a year. One hundred of the subjects chose an overlay as improving
their immediate perception of text. These subjects were significantly more
likely to report perceptual distortions and visual discomfort on viewing text
than subjects who did not choose an overlay. The 100 subjects read 3.8% faster
with the overlay than without any overlay (p < 0.00001), whereas the 13 subjects
who did not choose an overlay read 1.7% slower with a placebo overlay than
without (p = 0.37). Of the subjects who chose an overlay, 38% read more than 5%
faster with the overlay and 2% read more than 25% faster. These results are
comparable with those obtained for children. We conclude that Meares-Irlen
Syndrome is likely to be as common in adults as it is in children.