Dyslexia and Scotopic Sensitivity are two separate issues. Dyslexia has to do with language processing (reading, writing, spelling, word retrieval, memorization). Scotopic Sensitivity (Irlen Syndrome) has to do with light spectrums and how it effects what you see. Two totally different things which can be present in one individual, or they can be independent of one another. Just because you have one doesn't mean you have both.
Not a lot is known about Scotopic Sensitivity (Irlen Syndrome).
There is a lot of research on Dyslexia and how to teach language based skills to someone with dyslexia--you just have to watch out for the snake oil! NIH has established protocols for testing and also recommends Orton-Gillingham based methods for teaching someone with dyslexia. There is no cure for either one, but there are resources and tools that can help.