Convergence insufficiency or Convergence Disorder is a sensory and neuromuscular anomaly of the binocular vision system, characterized by an inability of the eyes to turn towards each other, or sustain convergence.

[edit] Symptoms

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, abnormal fatigue, headache, and abnormal postural adaptation, among others. Note that some Internet resources confuse convergence and divergence vergence dysfunction, reversing them.

[edit] Diagnosis

Diagnosis of convergence insufficiency is made by an eye care professional skilled in binocular vision dysfunctions to rule out any organic disease. Convergence insufficiency characterized by one or more of the following diagnostic findings: High exophoria at near, reduced accommodative convergence/accommodation ratio, receded near-point of convergence, low fusional vergence ranges and/or facility.

[edit] Treatment

Convergence insufficiency may be treated with convergence exercises prescribed by an eyecare specialist trained in vision therapy, orthoptics, and binocular vision anomalies. http://www.covd.org/Home/Convergence/tabid/89/Default.aspx. Some cases of convergence insufficiency are successfully managed by prescription of eyeglasses with therapeutic Prism (optics) and/or lenses in addition to the therapy regime.

In 2005, the Convergence Insufficiency Treatment Trial (CITT) published two randomized clinical studies. The first, published in Archives of Ophthalmology demonstrated that in-office based vision therapy was more effective than home based treatment for convergency insufficiency in 9 to 18 year old children.^[1] The second found similar results for adults 19 to 30 years of age.^[2]

[edit] Prevalence

A British survey found that less than 1 in 300 patients receiving optometric eye examinations had convergence insufficiency^[3] and a Spanish study found that nearly 1 in 100 (0.8%) of symptomatic patients in an optometric clinic had CI.^[4] 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^[5] as did nearly 1 in 5 (17.6%) of 8 to 12 year olds receiving examinations at optometry clinics.^[6] 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.^[7]

[edit] References

[edit] See also

• Amblyopia
• Negative relative accommodation
• Positive relative accommodation
• Strabismus
• Orthoptics

[edit] External links

• www.convergenceinsufficiency.org
• International Orthoptic Association
• College of Optometrists in Vision Development
• New York Times article on convergence insufficiency
• Vision Disorder Responds Best to Office-Based Therapy Combined with Home-Based Computer Therapy peer-reviewed article from MedPage Today