What is convergence insufficiency?
Convergence insufficiency is one of the most common vision disorders that interferes with a patient's ability to see, read, learn and work at close distances. It was recently the focus of a scientific study in the United States funded by the National Institutes of Health and the National Eye Institute. The study found that in-office Vision Therapy was the best available treatment for convergence insufficiency, replacing conventional therapies such as "pencil push-ups", with 75% of patients showing significant improvement following vision therapy.
Convergence insufficiency is a vision problem where the two eyes don't work together in unison the way they should. With convergence insufficiency the eyes have a strong tendency to drift outward when reading or doing close work. The result can cause double vision and, at minimum, make reading and learning very difficult.
The good news is the majority of these vision problems can be treated with a program of optometric vision therapy.
Even though the study by the NEI found that in-office vision therapy was the best treatment for convergence insufficiency, some doctors who are not up-to-date on the latest scientific research still tell their patients that "pencil push-ups" are the only treatment available that if if "pencil push-ups" don't work the patient is out of luck. This is not correct. The NEI study found that in-office vision therapy was significantly more effective than "pencil push-ups" and the only treatment that was more effective than a placebo. A number of follow up studies have been done; you may read about these on the binocular vision page.
The latest research on convergence insufficiency
There have also been follow-up studies by Scheiman et al. showing that the results obtained from vision therapy are were long-lasting and that the treatment kinetics are favorable – meaning that that rate at which patients get better with vision therapy makes office-based vision therapy an effective and practical treatment.
In 2005 Scheiman et al. published a clinical trial in Optometry and Vision Science on the vision therapy treatment of convergence insufficiency in young adults ages 19-30. Once again, the results proved the efficacy of vision therapy treatment over other modalities that were in use at the time. The study authors concluded:
This first multicenter, randomized clinical trial of the treatment of symptomatic CI in young adults demonstrated that of the three treatment modalities, only vision therapy/orthoptics was effective in achieving normal clinical values for both the near point of convergence and positive fusional vergence. Patients in the pencil pushups group achieved normal values only for positive fusional vergence at near and patients in the placebo vision therapy/orthoptics group did not achieve normal findings for either the near point of convergence or positive fusional vergence at near. Therefore, the effectiveness of vision therapy/orthoptics in improving the near point of convergence and positive fusional convergence values at near in adults cannot be explained on the basis of a placebo effect. Based on the results of this preliminary study, it would appear that pencil pushups, the most popular treatment for CI, is not effective for achieving clinically significant improvements in symptoms or signs associated with CI in young adults.
A study published in 2010 by Alvarez et al. in Optometry & Vision Science adds to the depth of the scientific evidence by showing that vision therapy produced demonstrated changes in eye movements together with significantly increased functional activity within the frontal areas of the brain, the cerebellum, and brain stem. These regions of the brain are likely to ―participate in a collicular-cortical dorsal visual networks and may reflect increased processing of visual material specific to near space. This study demonstrates the motor and neurological mechanism by which vision therapy operates.
The brain scan images published in the Alvarez study show changes in the brain before and after vision therapy and at a follow up MRI scan:
Symptoms of convergence insufficiency
The most common signs that your child is suffering from convergence insufficiency are the following:
- eyestrain (especially with or after reading)
- blurred vision
- double vision
- inability to concentrate
- short attention span
- frequent loss of place
- squinting, rubbing, closing or covering an eye
- sleepiness during the activity
- trouble remembering what was read
- words appear to move, jump, swim or float
- problems with motion sickness and/or vertigo
It is estimated that least one out of every 20 school-age children is impacted by convergence insufficiency. Some studies even put the number as high as 15%. However, there are other visual abnormalities to be considered.
Is your child smart in everything except school?
This is what reading can be like with convergence insufficiency