|Difficulty converging while engaged in a reading task causes misalignment of the eyes results in double vision unless the individual exerts additional convergence effort to re-align the eyes. As the visual system attempts to eliminate this double vision by using additional convergence effort, a number of significant symptoms can occur. These symptoms, include frequent loss of place, loss of concentration, having to re-read, reading slowly, trouble remembering what was read, sleepiness, blurred vision, diplopia, headaches, and/or eyestrain during reading or other near work.
The Convergence Insufficiency Treatment Trial Investigator Group recently gathered important data about the symptoms of convergence insufficiency in a series of studies (2008 Reference, 2005 Reference). These were the first studies that used a scientifically valid and reliable symptom questionnaire.
These studies found that children with convergence insufficiency reported that the following symptoms occurred “fairly often” or “always” while reading or doing close work:
|Loss of place:||50%|
|Loss of concentration:||45%|
|Re-reading the same line:||45%|
|Trouble remembering what was read:||38%|
|Eyes feel tired:||30%|
|Eyes feel uncomfortable:||29%|
|Eyes feel sore:||21%|
An interesting finding from these studies was that performance related symptoms (e.g. loss of place, loss of concentration, re-reading the same line, reading slowly, trouble remembering what was read or feeling sleepy) occurred more frequently than eye related symptoms (e.g. blur, headache, diplopia, or asthenopia). This finding is important because it demonstrates that children and adults with convergence insufficiency are likely to experience performance problems when reading.
It is also important to note that the second most common symptom was loss of concentration with almost ½ children reporting this symptom fairly often or always when reading. This potential link between convergence insufficiency and attention disorders has important practical implications for educators, physicians, psychologists other professionals involved in the detection, diagnosis, and treatment of attention deficit hyperactivity disorder. It suggests that a comprehensive vision examination should be mandatory for any child with a suspected attention problem to rule out convergence insufficiency.