One thing Lisa has mentioned over and over that everyone who suffers from any sort of LD experiences it differently. There is no exact definition for any of them. This post by a dyscalculic is a great example
"The realisation that I couldn't see images in my mind was quite a surprising one; probably because I thought something this major would have been noticed, least of all by me in the 25 years in which I have been conscious!"
Feeling a bit cheated since most dyscalculics exhibit strong visualization abilities. But it's interesting to note that the poster is an artist.
"My introspection on this came after reading several self-help books on dyslexia, all of which emphasised how great dyslexic/dyscalculic people are at visualisation and how this great faculty makes up for the verbal/ numerical deficits. They even propagated that the strength of the minds eye was the reason that so many people with learning difficulties go on to do great creative things. After reading this time and time again, I felt cheated and robbed - where was my great visual faculty? This is what initiated my journey of introspection on the minds eye and also uncovered the surprising discovery that my visual faculty was not in the least 'superior' but almost non existent."
It's an interesting read you might take a look at.
How to build a visual picture