The first link is a technical, but interesting review of the findings that led up to the discovery that the brain has a specialized clusters of neurons that recognize strings of letters that make up 'words'. Dyslexic individuals who have problems with 'visual word form' may have difficulty spelling and sometimes recognizing non-phonetic words (for instance 'their').
Visual word form weakness can look perplexing to others because these individuals are often very bright, but seem to labor at recognizing or even seeing whole words at once...preferring instead to identify words 'letter-by-letter'.
Interestingly, strategies for overcoming visual word form weakness usually succeed if they build on the strengths in other pathways - for instance auditory memory, or other visual memory systems that may involve color or picture recognition. Blocks in visual word form memory do exist, but they can be overcome with a skillful redirection of learning to emphasize alternative memory systems in the brain.
The second article discusses the particular difficulties of English and French for dyslexics. Some dyslexic students may foreign language waiver because of the severity of their language processing difficulties. If some foreign language must be chosen, then Spanish or Italian (both more predictable re: spelling and phonetics)or ASL might be the best choices.
Dehaene review on Visual Word Form
Dyslexia harder on English- and French-speaking Children