Just like Dyslexia, Irlen Syndrome often occurs in families. It is certainly not unusual to have a mom or a dad that accompanies their child to a screening end up with a reading overlay themselves (often to help them work from a computer, where they have particular difficulty).
Last week I saw a 9 year old boy (previously screened at school) who was coming to me for the special Irlen tints to be worn as glasses. During the screening his mom had many questions about Irlen Syndrome and when I was showing how different colors helped her son cope with fluorescent lighting and enabled him to look out of a window without squinting she asked if light sensitivity on its own (without a person experiencing distortions in the environment or a reading difficulty) could be due to Irlen Syndrome. I replied that light sensitivity was a key symptom and people needed different combinations of colors to help combat it. Mom works as a photographer, often needs sunglasses and has particular difficulty working on a computer editing the videos she produces. As we progressed with the diagnostic she too chose some colors to enable her eyes feel comfortable as we increased the lighting and she was surprised when she looked at the eye chart that the letters also became clearer! Of course people with Irlen Syndrome do not know that the way they see the environment, letters and numbers is not the same as everyone else.
People with Irlen Syndrome also wear hats with style as they can be sensitive to any light that gets around frames and into their eyes - especially from above or the side (see photo!)