Grisham et al. (2007) studied 461 American high school students (mean age 15.4 years) identified as poor readers. Although only 17% had impaired visual acuity, 80% showed significant deficits in visual skills that affect reading—particularly synapse, or eye coordination, including convergence and focusing.
The study shows that standard syntheses do not capture these problems, and that many students with reading difficulties actually have completely normal visual acuity – one eye at a time – but difficulty coordinating both eyes when reading.
80% of 461 high school students with reading disabilities have preclinical problems with consensus