• astigmatism;
  • cataract;
  • decompensated exophoria;
  • dyslexia;
  • headache;
  • Meares–Irlen syndrome;
  • scotopic sensitivity syndrome;
  • vision


Meares–Irlen syndrome is characterised by symptoms of eye strain, headaches and visual perceptual distortions when viewing text. The symptoms are alleviated with individually prescribed coloured filters, such as precision tinted lenses. Meares–Irlen syndrome, and the related condition of visual stress, are likely to result from hyperexcitability of the visual cortex, which can also occur in migraine. The symptoms of Meares–Irlen syndrome and visual stress are non-specific and the condition needs to be differentially diagnosed from other optometric conditions, such as refractive error, binocular vision anomalies, and accommodative anomalies. Three case reports are described of patients who consulted the author with suspected Meares–Irlen syndrome but were found to have other causes for their symptoms: posterior sub-capsular cataract, high uncorrected astigmatism, and decompensated convergence weakness exophoria. These cases highlight the need for professional eye care for people with suspected Meares–Irlen syndrome. Although this advice is stressed in literature on the well-established MRC/Wilkins Intuitive Colorimeter system, it is not always stressed in literature about other systems. This may be a cause for concern.