|What is convergence insufficiency?|
Convergence Insufficiency (CI) is a common binocular (two-eyed) vision disorder in which the eyes do not work at near easily. An eye teaming problem in which the eyes have a strong tendency to drift outward when reading or doing close work (exophoria at near). If the eyes do drift out, the person is likely to have double vision.How Common is Convergence Insufficiency?
To prevent double vision, the individual exerts extra effort to make the eyes turn back in (converge). This extra effort can lead to a number of frustrating symptoms which interfere with the ability to read and work comfortably at near.
Convergence insufficiency has a reported prevalence among children and adults in the United States of 2.5 to 13%What are the Symptoms of Convergence Insufficiency?
A person who has convergence insufficiency may show and/or complain of the following while doing close work (i.e., reading, computer work, deskwork, playing handheld video games, doing crafts, etc.): What is the most effective treatment for convergence insufficiency in children?
- 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
When comparing various clinical treatments for a medical condition such as convergence insufficiency, the gold standard research method is referred to as a RANDOMIZED CLINICAL TRIAL. Until recently there were no randomized clinical rials available in the ophthalmic literature about treatment of convergence insufficiency. Fortunately since 2005 two such studies have been published.
The results of theses studies clearly indicates that office-based vision therapy with home reinforcement is the most effective treatment for convergence insufficiency. These studies (link) showed that office-based vision therapy was ore effective than either home-based pencil push-ups or home-based computer vision therapy. The studies also used a placebo control to rule out the placebo effect.
The 2008, large scale study (link) demonstrated that about 75% of the children in the office-based vision therapy group were classified as "successful" or" improved" after 12 weeks of therapy compared to only 43%, 33%, and 35% of patients in the home-based pencil push -ups, home-based computer vision therapy, and office-based placebo groups.Do the results of office-based vision therapy last after the patient discontinues the treatment?
In the large-scale, randomized clinical trial on 221 children with convergence insufficiency which was published in 2008 we found that office-based vision therapy was more effective than home-based treatments after 12 weeks of treatment.
We recently presented the long-term data from this study. The study will be published in Optometry and Vision Science in July 2009.
We followed all children who were no longer symptomatic at 12 weeks. They were re-examined at 6 and 12-months after completion of their treatment.
The results show that about 90% of the children in the office-based vision therapy group remained asymptomatic one year later. Most children who were in the home-based groups also remained asymptomatic, although not as high a percentage as in the office-based group.
Is there any research about the effectiveness of base-in reading glasses for convergence insufficiency?
Yes, in 2005 we the CITT Investigator group completed a randomized clinical trial comparing the effectiveness of base-in prism reading glasses and placebo reading glasses. The results, published in the British Journal of Ophthalmology, showed that the base-in prism glasses were no more effective than placebo glasses. Our conclusion was that base-in prism reading glasses is not an effective treatment for children with symptomatic CI. Is there research about the effectiveness of pencil push-ups for convergence insufficiency
The CITT Investigator group has completed the only two randomized clinical trials that have investigated the use of pencil push-ups. In both studies the results showed that pencil push-ups are no more effective than placebo treatment. How many office visits are generally required to successfully treat CI?
The American Optometric Association's Clinical Practice Guideline suggest that about 12-24 visits may be required. In a recently completed clinical trials showed that 12 weeks (visits) of office-based vision therapy resulted in about a 75% success rate. This study was not designed to determine the maximum effectiveness of office-based vision therapy. It appears that a minimum of 12 weeks are required and more visits may lead to better results. Are there any clinical trials currently recruiting children with convergence insufficiency?
Yes, the Convergence Insufficiency Treatment Trial - Attention and Reading Study (CITT-ART), funded by the National Eye Institute (NEI), is currently recruiting patients.