ADHD-affected individuals often have trouble reading for long periods. Many report trouble concentrating, experience headaches, sleepiness, and restlessness while attempting to read. The problem is then conceived and tackled solely on a cognitive or brain-based dimension. Interestingly, the condition of "convergence insufficiency", which denotes drifting of the eyes inward or outward, can be a contributing factor. The effort it takes for the ocular muscles to correct this problem leads to strain, tiredness, restlessness, and headaches. The solution lies either in in-office vision therapy or prism glasses. You can look into this by first discussing it with an optometrist or ophthalmologist who is familiar with this underdiagnosed condition. I found a skilled optometrist in the Cleveland who has a special interest in this area, Dr. Phillip Skovira. The wonder never ends with ADHD-related issues!