is a sensory and neuromuscular anomaly of the
Binocular Vision system, characterized by an inability to converge the
Eye s or sustain
Convergence .
The symptoms and signs associated with convergence insufficiency are related to prolonged, visually-demanding, near-centered tasks. They may include, but are not limited to,
Diplopia (double vision),
Asthenopia (eye strain), transient blurred vision,
difficulty sustaining near-visual function, Aanormal fatigue,
Headache , and abnormal postural adaptation, among others.
Diagnosis of convergence insufficiency is made by an eye care professional skilled in at near, reduced
Accommodative-Convergence/Accommodation Ratio , receded
Near-point Of Convergence , low
Fusional Vergence Ranges and/or facility.
Some cases of convergence insufficency are successfully managed by prescription of
Eyeglasses with therapeutic
Prism (optics) and/or
Lenses . However, most convergence insufficiencies require
Orthoptics or
Vision Therapy .
Very recently, the Convergence Insufficency Treatment Trial (CITT) published two large, randomized clincal studies. The first demonstrated that in-office based vision therapy was more effective that home based treatment for convergency insufficiency in 9 to 18 year old children. The second, found similar results for adults 19 to 30 years of age .
A British survey found that less than 1 in 300 patients receiving optometric
Eye Examination s had convergence insufficiency and a Spanish study found that nearly 1 in 100 (0.8%) of symptomatic patients in an optometric clinic had CI . In contrast, studies conducted by the
Southern California College Of Optometry found that approximately 1 in 8 (13%) of fifth and six grade children examined during visual screenings had the disorder as did nearly 1 in 5 (17.6%) of 8 to 12 year olds receiving examinations at optometry clincs . A recent Romanian study revealed that roughly 3 in 5 (60.4%) of young adult patients complaining of blurred vision at near work suffered from convergence insufficiency .
