Dyslexic Readers can commonly have subtle visual problems (binocular instability &/or visual stress) & these may not be detected in routine eye tests. An optometrists or orthoptists would be able to detect these problems.
This would not be visible when looking at someone’s eyes however it could cause problems if the person was reading. Below are some common symptoms:
Visual Stress can be caused by difficulties seeing high contrast detail. Below are some common symptoms:
Coloured filters or lenses can help ease visual stress however the colour needed will be different for each individual.