Irlen Syndrome, dyslexia or both?

I’m often asked by clients, “So if my child has Irlen Syndrome, does that mean they are dyslexic?”

These two conditions often overlap, but they can also stand alone and a person with dyslexia may not have Irlen Syndrome and vice versa. This is why it is so important for me to look at both conditions, when a person comes to me for an assessment.

NOTE: At the end of this post is an excellent TEDEd video, particularly at 0:56 where it states that ‘dyslexia’ is a phonological processing problem where people have trouble manipulating language.


This is where dyslexia differs the most from Irlen Syndrome, as Irlen Syndrome is a visual perception problem, where difficulties cannot necessarily be explained by phonetic deficits or by a weak sight vocabulary. Faulty reading occurs, often characterised by omissions and additions.

Glare, lighting, contrast, patterns and colours impact this syndrome and individuals commonly suffer from any of the following: slow reading rate, inefficient reading, poor reading comprehension, inability to do continuous reading, strain and fatigue while reading, difficulties with depth perception or sport performance.

Meares-Irlen Syndrome or Scotopic Sensitivity Syndrome as it is also known, can affect attention span, concentration, motivation, work production and classroom performance.

Individuals with Meares-Irlen Syndrome/SSS might have been considered to be underachievers, who may have been told they “could do better” if they “tried harder”. Some individuals have been misdiagnosed with behavioural or attitudinal problems or as having ADD, hyperactivity, or reading disabilities. Meares-Irlen Syndrome/SSS also occurs on a continuum, from very slight to very severe, depending on the type, onset, number and intensity of the distortions.

Irlen Spectral Filters are lenses, that are individually spectrally modified to eliminate or reduce the perceptual problems and act as filters, selectively reducing the input of specific wavelengths of light that allow receptor cells in the retina or others in the cerebral cortex to more effectively analyse visual information.


Where Dyslexia and Irlen Syndrome are most similar is in the need to stress the importance of a work program that presents new skills using a cumulative, structured and sequential approach that allows for overlearning.

Using a multisensory approach to teaching, across the curriculum, by-passes the organisational difficulties in the brain, integrating learning pathways and helping to store and retrieve information.

View this informative video from TEDEd by Kelli Sandman-Hurley (4 min)

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