Dyslexia is a reading disability that is characterised by difficulties of reading, decoding and spelling. In order make online materials accessible for people with dyslexia, developers should make on-screen presentation of text adaptable. There is very little research that has empirically tested which text presentations and web navigation are helpful or acceptable to people with dyslexia. Therefore two studies are conducted on the aspect of text presentation, Study 1 focused on the effects of typefaces and font size while Study 2 focused on the effects of line spacing and line length. Study 3 focused on the effects on menu organisation and visibility on web navigation. All three studies compared English native speaking adults with and without dyslexia on their eye gaze behaviour, performance, preferences and opinions. For the text presentation studies, the dyslexic participants were grouped into more specific categories, mild and moderately dyslexic, based on the results of a well-established checklist for identifying dyslexia. Eye gaze tracking was measured in all studies. Findings from the studies on text presentation show that all participants had fewer fixations with small font size, shortest fixation durations with dyslexia-optimised typefaces, and fewer and shorter fixations with longer line length. Participants preferred sans serif typeface and wider line spacing. There were different levels of comfort with dyslexia-optimised typefaces for non-dyslexic and dyslexic participants. Findings from the study on web navigation show that fragmented menus with visible sub-menus had fewer fixations, while dynamic sub-menus had fewer revisits and fewer fixations. However unified menus were rated as easier to use, to remember and to learn. Participants with dyslexia show poor performance in both text presentation and web navigation studies. Key contribution of this programme of research is to the methodology of studies to investigate text presentation on screen and web navigation effects for people with dyslexia
