As a dyslexia tutor, I often work on reading comprehension with my dyslexic students in addition to our regular reading time. Reading comprehension is challenging for many children, and particularly so with dyslexic children. One of the reasons for this fact is that sometimes, a dyslexic child simply cannot properly read the words that they are expected to understand and digest.
As you can imagine, if you were to take a paragraph and find that you have difficulty with a decent percentage of the words, you might have a difficult time understanding exactly what the paragraph was saying. Many dyslexic children end up skipping over difficult words, and as a result, are only getting a portion of the picture when they read something. A good dyslexia tutor will address this issue, and work with the child until they form a new habit of stopping at difficult words and applying their knowledge to figure it out.
Another reason that a dyslexic child may have difficulty with reading comprehension is because of word skipping. Word skipping is extremely common among dyslexics, and this can cause them to misread sentences, even when they are reading most of the words correctly. A dyslexic child who skips words may correctly read many of the words, but still not understand the intended meaning of a sentence.
Overall, reading comprehension is defintely a skill that can be improved with practice. In addition to helping a dyslexic child learn the mechanics of reading, a good dyslexia tutor can also help them develop reading and comprehension strategies. For materials, there are comprehension books that provide good practice with reading and answering questions about content and words. Or, you can always practice comprehension with a regular book by asking the child questions about what they have just read after every few pages. Reading comprehension is a vital skill in life, and it should be taught and practiced on a regular basis.