well, the definition of dyslexia keeps on changing, but I get a bit tired of the niggly little pendants who try and catagorise every one in this exact definition, or that.
Dyslexia is an umbrella term for neurological abnormalities leading to difficulties in visual/tactile perception and/or expression.
As in difficulty reading, because you cannot interpret what you can clearly SEE.
But anyone with any common sense would realise that if you are unable to work out exactly what you are looking at when you are looking at WORDS, then you are also going to have difficulties working out exactly what you are looking at when you are looking at other things too.
such as maps/ sequences/faces/colours etc.
There isn't one part of the brain that interprets letter shapes, separate from other parts of the brain interpreting other things. Its not like just the letter perceiving part of the brain can go wrong and leave your brain able to do other related tasks - because the related tasks are done by the same part of the brain.
I am dyslexic, because, in spite of a genious level IQ, I am not able to read easily. or spell easily.
But the issues with writing are not the only manifestation of neurological perceptoal and expressive abnormalities. Of course they wouldn't be.
Colours make a HUGE difference to me - I am using sunglasses to read the computer screen right now. I can't see ( ie perceive) high contrasts at all. I can see how coloured overlays would help a lot - I have some somewhere, but sunglasses are easier.
By most of your definitions I am dyslexic, and it IS a visual problem - not seeing, but percieving ( I also have poor tactile perception, can't tell my keys from my money in my pocket, for example)
however, my memory is excellent, short and long term, so although I clearly fall into the catagory of "dyslexic" I don't fit your stereotype of no visual problems, and poor memory.
in fact, I think a lot of dyslexics develop their memory to closer to its full potential, compared to non dyslexics. I am much better at reading sentences than reading lists, for example, because I can follow the line more easily than I can jump forwards and backwards to read each item on a list. Therefore, although I do write shopping lists, I don't rely on them. I remember them too.