Convergence insufficiency

Convergence Insufficency
Classification and external resources
ICD-10	H51.1
ICD-9	378.83
eMedicine	oph/553
MeSH	D015835

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.

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 dysfunction, reversing them.

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.

Treatment

Convergence insufficiency may be treated with convergence exercises prescribed by an eyecare specialist trained in vision therapy, orthoptics, and binocular vision anomalies. Some cases of convergence insufficiency are successfully managed by prescription of eyeglasses with therapeutic prisms 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 computer exercises when combined with in-office based vision therapy was more effective than "pencil pushups" or computer exercises alone 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]

Surgical correction options are also available, but the decision to proceed with surgery should be made with caution and only after all orthoptic efforts have failed.

Bilateral medial rectus resection is usually the most effective operation for convergence insufficiency. However, the patient should be warned about the possibility of uncrossed diplopia at distance fixation after surgery. This typically resolves within 1-3 months postoperatively. The exophoria at near often recurs after several years, although most patients remain asymptomatic.

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]

References

1. ^ Scheiman M, Mitchell GL, Cotter S, Cooper J, Kulp M, Rouse M, Borsting E, London R, Wensveen J; Convergence Insufficiency Treatment Trial Study Group. "A randomized clinical trial of treatments for convergence insufficiency in children." Arch Ophthalmol. 2005 Jan;123(1):14-24. PMID 15642806.
2. ^ Scheiman M, Mitchell GL, Cotter S, Kulp MT, Cooper J, Rouse M, Borsting E, London R, Wensveen J. "A randomized clinical trial of vision therapy/orthoptics versus pencil pushups for the treatment of convergence insufficiency in young adults." Optom Vis Sci. 2005 Jul;82(7):583-95. PMID 16044063.
3. ^ Stidwill D. "Epidemiology of strabismus". Ophthalmic Physiol Opt. 1997 Nov;17(6):536-9. PMID 9666929.
4. ^ Lara F, Cacho P, Garcia A, "Megias R. General binocular disorders: prevalence in a clinic population." Ophthalmic Physiol Opt. 2001 Jan;21(1):70-4. PMID 11220042.
5. ^ Rouse MW, Borsting E, Hyman L, Hussein M, Cotter SA, Flynn M, Scheiman M, Gallaway M, De Land PN. "Frequency of convergence insufficiency among fifth and sixth graders. The Convergence Insufficiency and Reading Study (CIRS) group." Optom Vis Sci. 1999 Sep;76(9):643-9. PMID 10498006.>
6. ^ Rouse MW, Hyman L, Hussein M, Solan H. "Frequency of convergence insufficiency in optometry clinic settings. Convergence Insufficiency and Reading Study (CIRS) Group." Optom Vis Sci. 1998 Feb;75(2):88-96. PMID 9503434.
7. ^ Dragomir M, Trus L, Chirila D, Stingu C. "[Orthoptic treatment efficiency in convergence insufficiency treatment]". Oftalmologia. 2001;53(3):66-9. PMID 11915694.

See also

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

External links

• www.convergenceinsufficiency.org
• College of Optometrists in Vision Development
• International Orthoptic Association
• 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