Web site design. Everyone is susceptible to eye strain and tiredness when working. When a person concentrates for a long period on a particular piece of text, the words may go blurry though this is only temporary. Someone who is tired or stressed can make mistakes when reading. Dyslexic people frequently experience visual discomfort when reading.
Some dyslexic people focus on the spaces rather than on the words.
This is often described as seeing rivers moving down the page. The words and text can appear to be moving around the page or wobbling. Anyone with a history of reading difficulties may have to concentrate harder to interpret text and remember what they have read. Anything that disturbs concentration, such as visual discomfort, exacerbates the problem. Black print on shiny white paper causes most discomfort.