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Convergence Insufficiency

Convergence insufficiency is the most common eye muscle disorder among children and adults.


When we read or look at anything close, the eyes have to cross (or converge) slightly in towards the nose to allow single vision. Convergence insufficiency results from difficulty  maintaining the eyes in this crossed posture. When convergence is reduced, the individual must exert excessive effort to maintain single vision. This typically causes headaches, eye strain, burred vision and double vision during sustained reading or close work.

convergence insufficiency sample text
Source: College of Optometrists in Vision Development

Children with convergence insufficiency will often:

  • lose their place when reading
  • rub their eyes when doing close work
  • cover or close one eye
  • avoid reading, and have poor attention during reading and homework
  • fatigue rapidly and  take frequent breaks

Convergence insufficiency is more common in children with a diagnosis of ADHD. Convergence insufficiency generally does not interfere with learning how to read (word recognition and decoding), but can interfere with reading comprehension and fluency, especially as children are expected to read for longer periods of time. Both comprehension and fluency often become worse the longer the child reads.

Research On Convergence Insufficiency

Convergence insufficiency is present in 3% to 5% of children and adults, and has been extensively researched. The Convergence Insufficiency Treatment Trial (CITT) was a nationwide randomized clinical trial funded by the National Eye Institute, and it was preceded by several other randomized clinical trials.  CITT compared in-office vision therapy to two types of home-based vision therapy as well as office-based placebo therapy. The results were published in 2008 in Archives of Ophthalmology, and showed that office based therapy was superior to the other treatments. Both home-based treatments did not work any better than placebo treatment. CITT-ART was completed in 2019 and found similar results. Dr. Gallaway was the Principal Investigator at Salus University for both CITT and CITT-ART.

An article from an ophthalmology journal reviewed the recent studies and concluded that office-based vision therapy is the treatment of choice for convergence insufficiency.

Other research articles from the CITT study have shown that the positive treatment effects were still present a year later, vision therapy improved parent-rated academic behaviors, and that accommodation (focusing ability) improved also.

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