In the u.s., reading small words with speed is referred to as having a large base of 'sight words': 'the','and' & 'it' are the usual focus, things that you read millions of times and just would not want to sound out after even a few months of reading. It sounds very much like visual issues would affect this skill from firming up quickly - entirely non-expert opinion here!
On the other hand, I don't know that ds ever had to practice less common words or what look more like parts of words - pom, dom, etc. Sort of scratching my head there...
I think you are on a good path in looking for alternate methods of developing this skill. I would focus on words which make sense as beginning sight words, as noted above, hopefully others will be able to chime in with some good advice - very best of luck!
