'Symptoms of Visual stress include illusions of shape, movement and colour in the text, distortions of the print, loss of print clarity, and general visual irritation. Visual stress can also cause sore eyes, headaches, frequent loss of place when reading, and impaired comprehension.' For more information click here.
Over the last 20 years or so tinted overlays and/or tinted spectacle lenses have been suggested to reduce symptoms of visual stress. At first their use caused a great deal of controversy and it was argued that any perceived improvement in reading was due to a placebo effect. However recent research into visual processing has shown that there are physiological reasons why reading fluency may be affected by the colour of text and its background. Not all Community Opticians will screen for the use of overlays and/or offer colorimetry (a test to determine the specific colour of spectacle lenses needed), but most should be able to refer you on to a colleague who does. This aspect of sight testing is not paid for by the NHS, so an additional fee will be charged.