Convergence Disorders Affecting Reading
Convergence (eye teaming and coordination) problems will impair reading ability. Difficulty with the eyes working together can cause double vision, eyestrain, fatigue, or the appearance of words seeming to move and swim on the page when reading. Options for treatment include lenses, prisms, and therapy.
Accommodation Disorders Affecting Reading
Accommodation (focusing) problems will impair reading ability. Difficulty with how the eyes focus can cause blur, eyestrain, fatigue, or the appearance of words seeming to pulse and float on the page when reading. Options for treatment include lenses and therapy.
Reading Problems Due to Visual Field Loss
Visual field (peripheral vision) loss will often interfere with reading ability. Patients often lose their place and miss words to the side of the loss while reading. Treatment options include the use of special prisms, scanning therapy and compensatory reading techniques.
Visual Impairment Causing Reading Problems
Visual impairment (loss of visual acuity for example with macular degeneration) will impair reading. The problem is directly related to clarity of sight, and since most reading material is fairly small print, reading is thus impaired. Therapy options aim at enhancing visual acuity. Low vision techniques including special microscopic lenses, telemicroscopes, magnifiers, and electronic closed circuit television systems may help the patient read again.
Diplopia Causing Reading Problems
Diplopia (double vision) is the most bothersome and intolerable of vision problems and will impair reading. There are many types of diplopia (see section on double vision). Treatment options include lenses, prisms, partial selective occlusion and in very rare circumstances surgery.
Eye Gaze Disorders Affecting Reading
Eye gaze disorders, called ophthalmoplegia (paresis or paralysis of eye muscles that limit ability to move the eye in certain directions) will affect reading. Patients with inferior gaze problems may not be able to look down into their bifocal. Patients with lateral gaze problems may experience scanning problems or diplopia. Treatment options include lenses, prisms, and compensatory reading strategies.
Eye Movement Disorders Affecting Reading
Saccadic (scanning) movements of the eyes are required when reading and when dysfunctional will impair reading. Saccadic disorders manifest as jerkiness or slowness of movement. The eyes may jump erratically when reading causing loss of place, skipping lines, or re-reading lines of print when reading. Treatment is with eye movement therapy to improve the saccadic movements.
Combination of Two or More of the Above
In reality most of the patients I see have a combination of visual problems, which make it difficulty for the patient and family to understand the exact cause. I recommend a comprehensive vision examination on all head injury patient experiencing reading difficulty.
