I agree with knute and aculady. The WISC cannot be used to diagnose dyslexia, but can be used along with a battery of other tests. Low scores in the PSI and WMI are often a red flag for a LD - but in and of itself, cannot diagnose a reading disability.
Visual motor issues may impact scores on certain subtests such as block design, symbol search and coding.
Depending upon how one defines dyslexia, scores in the VCI may be affected by dyslexia.
These tests are often used to diagnose dylsexia (and to pinpoint the type of reading problem):
Grey Oral Reading IV
WJRMT
Test of Word Reading Efficiency
CTOPP
Tests of reading achievement various subtests in the Woodcock Johonson, WIAT, Kaufman etc batteries
Very often people with dyslexia also have speech/ language processing difficulties - a full speech and language evaluation can shed light.
