Prof. Wilkins of the University of Essex has produced some very interesting research. He had found that there were substantial numbers of children helped by being assessed and then offered the use of coloured plastic overlay when reading. Some children had quite severe difficulties, with dramatic results being seen with use of an overlay. Many were made more comfortable with regards to reading; with academic gains as a consequence. The research results equated to the equivalent of a whole secondary school in an average LEA benefiting from the use of an overlay. This was very exciting from the point of view of raising achievement, let alone individual effects, such as enhanced exam grades, life chances, increased self esteem etc. The assessment instrument devised by Prof. Wilkins is the Intuitive Overlays Test.
If you or your child is experiencing visual effects such as: text wobbling, moving, flickering, blocking out, underlining, halo effects, head aches, a feeling of over brightness, then it would be useful to have an assessment of scotopic sensitivity.