The party line in my school district is that dyslexia is a medical diagnosis. Nobody in the school system is qualified to make that diagnosis.
The WISC, in combination with an academic assessment such as the WIAT or WJ can help identify significant gaps in achievement to help with eligibility decisions or educational programming. A doctor may find these assessment results helpful when making a diagnosis.
The school system does not need this diagnosis to move forward with a program. The term "dyslexia" is one that the general public believes has more meaning than "specific learning disability", but school psychologists and special education teachers are looking for other, more specific information, anyway. Learning that a student is dyslexic does not actually tell us, specifically, what the student's educational needs are. We have other ways to find that out, including the WISC and a whole alphabet soup of assessments.
Naturally, there are other opinions, hypotheses, and stances, even within our school system.
