Normal vision encompasses more than good eyesight. Some people find that although they can see perfectly clearly, there are specific patterns that cause visual disturbance and discomfort.1 The solution is tinted lenses – colour filters which reduce perceptual discomfort and provide relief from symptoms.2 Our Adelaide practice is equipped with a colorimeter that can assess what tint is best suited to reduce your symptoms. If you suspect you would benefit from tinted lenses, book an appointment or contact us today.
'Pattern glare' is a collection of symptoms which often result in visual stress (Meares-Irlen Syndrome).3 It can become noticeable during tasks which involve looking at repetitive intermittent black and white lines. The most common of these scenarios is reading.
Pattern glare is caused when repetitive striped patterns hyperexcite the visual cortex of the brain. It can be tested for using the Pattern Glare Test, which involves presenting the patient with three different pattern on a piece of card. Of these three patterns, the first has spatial frequency that is too low to produce symptoms, and the last has a spatial frequency that is too high. The second pattern has a spatial frequency of 2-5 cycles per degree visual angle, at which each stripe subtends about 10 minutes of arc.
CAPTION: Image courtesy of Cerium Visual Technologies
The most obvious symptoms of pattern glare are eye strain, headaches, and light sensitivity.4 Pattern glare is particularly obvious when reading. Some symptoms that may arise during this activity include:
When projected on a white page with black text, certain wavelengths of light help to reduce symptoms provoked by pattern glare. The retinal image processed by the brain is more easily interpreted when there is a change in colour composition of the background on which the text is overlaid. The exact colour that best achieves this effect changes from person to person, which is why it’s important for patients with pattern glare to undergo colorimetry assessment. Once this optimal colour has been discovered, lenses for spectacles can be made with this tint to reduce eye strain and visual discomfort.5,6
Pattern glare often occurs without associated health conditions, although it can arise with concussion, epilepsy and dyslexia.7,8,9 It is important to see an optometrist if you believe you experience pattern glare, both as a step towards management of symptoms and also to affirm your overall well-being.