Convergence insufficiency

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

Convergence Insufficiency
Other namesConvergence disorder
SpecialtyOphthalmology, optometry 

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. In some cases, difficulty with making eye contact have been noted as a complaint amongst sufferers. 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, such as an orthoptist to rule out any organic disease. Convergence insufficiency characterized by one or more of the following diagnostic findings: Patient symptoms, High exophoria at near, reduced accommodative convergence/accommodation ratio, receded near point of convergence, low fusional vergence ranges and/or facility. Some patients with convergence insufficiency have concurrent accommodative insufficiency—accommodative amplitudes should therefore also be measured in symptomatic patients.

Treatment

Convergence insufficiency may be treated with convergence exercises prescribed by an eyecare specialist trained in orthoptics or binocular vision anomalies (see: Vision Therapy). Some cases of convergence insufficiency are successfully managed by prescription of eyeglasses, sometimes with therapeutic prisms.

Pencil push-ups therapy is performed at home. Patient brings a pencil slowly to within 2–3 cm of the eye just above the nose about 15 minutes per day 5 times per week. Patients should record the closest distance that they could maintain fusion (keep the pencil from going double as long as possible) after each 5 minutes of therapy. Computer software may be used at home or in an orthoptists/vision therapists office to treat convergence insufficiency. A weekly 60-minute in-office therapy visit may be prescribed. This is generally accompanied with additional in home therapy.[1]

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 office based vision therapy/orthoptics were more effective than "pencil pushups" or computer exercises alone for convergency insufficiency in 9- to 18-year-old children.[2] The second found similar results for adults 19 to 30 years of age.[3] In a bibliographic review of 2010, the CITT confirmed their view that office-based accommodative/vergence therapy is the most effective treatment of convergence insufficiency, and that substituting it in entirety or in part with other eye training approaches such as home-based therapy may offer advantages in cost but not in outcome.[4] A later study of 2012 confirmed that orthoptic exercises led to longstanding improvements of the asthenopic symptoms of convergence sufficiency both in adults and in children.[5] A 2020 Cochrane Review concludes that office-based vergence/accommodative therapy with home reinforcement is more effective than home-based pencil/target push-ups or home-based computer vergence/accommodative therapy for children. In adults, evidence of the effectiveness of various non-surgical interventions is less clear[6].

Both positive fusional vergence (PFV)[7] and negative fusional vergence (NFV)[8] can be trained, and vergence training should normally include both.[9][10] Surgical correction options are also available, but the decision to proceed with surgery should be made with caution as convergence insufficiency generally does not improve with surgery. Bilateral medial rectus resection is the preferred type of surgery. 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

Among fifth and sixth grade children convergence insufficiency is 13%.[11] In studies that used standardized definitions of Convergence insufficiency, investigators have reported a prevalence of 4.2% to 6% in school and clinic settings. The standard definition of Convergence insufficiency is exophoria greater at near than at distance, a receded near point of convergence, and reduced convergence amplitudes at near.[1]

See also

References
  1. Convergence Insufficiency Treatment Trial (CITT) Study, Group (Jan–Feb 2008). "The convergence insufficiency treatment trial: design, methods, and baseline data". Ophthalmic Epidemiology. 15 (1): 24–36. doi:10.1080/09286580701772037. PMC 2782898. PMID 18300086.
  2. Scheiman M, Mitchell GL, Cotter S, Cooper J, Kulp M, Rouse M, Borsting E, London R, Wensveen J, Convergence Insufficiency Treatment Trial Study Group (Jan 2005). "A randomized clinical trial of treatments for convergence insufficiency in children". Arch Ophthalmol. 123 (1): 14–24. doi:10.1001/archopht.123.1.14. PMID 15642806.CS1 maint: multiple names: authors list (link)
  3. Scheiman M, Mitchell GL, Cotter S, Kulp MT, Cooper J, Rouse M, Borsting E, London R, Wensveen J (Jul 2005). "A randomized clinical trial of vision therapy/orthoptics versus pencil pushups for the treatment of convergence insufficiency in young adults". Optom Vis Sci. 82 (7): 583–95. doi:10.1097/01.opx.0000171331.36871.2f. PMID 16044063.
  4. "Treatment of Convergence Insufficiency in Childhood: A Current Perspective". Optom Vis Sci. 86 (5). May 2009. pp. 420–428. doi:10.1097/OPX.0b013e31819fa712. PMC 2821445. PMC 2821445, NIHMSID:NIHMS153855
  5. Matti Westman; M. Johanna Liinamaa (May 2012). "Relief of asthenopic symptoms with orthoptic exercises in convergence insufficiency is achieved in both adults and children". Journal of Optometry. 5 (2). pp. 62–67. doi:10.1016/j.optom.2012.03.002.
  6. Scheiman M, Kulp MT, Cotter SA, Lawrenson JG, Wang L, Li T (2 December 2020). "Interventions for convergence insufficiency: a network meta-analysis". Cochrane Database Syst Rev. doi:10.1002/14651858.CD006768.pub3. PMID 33263359.
  7. P. Thiagarajan; V. Lakshminarayanan; W.R. Bobier (Jul 2010). "Effect of vergence adaptation and positive fusional vergence training on oculomotor parameters". Optom Vis Sci. 7 (87). pp. 487–493. doi:10.1097/OPX.0b013e3181e19ec2. PMID 20473234.
  8. K.M. Daum (July 1986). "Negative vergence training in humans". Am J Optom Physiol Opt. 7 (63). pp. 487–496. PMID 3740204.
  9. Mitchell Scheiman; Bruce Wick (2008). Clinical Management of Binocular Vision: Heterophoric, Accommodative, and Eye Movement Disorders. Lippincott Williams & Wilkins. p. 165. ISBN 978-0-7817-7784-1.
  10. Deshmukh, Saurabh; Magdalene, Damaris; Dutta, Pritam; Choudhury, Mitalee; Gupta, Krati (2017-07-01). "Clinical profile of nonstrabismic binocular vision anomalies in patients with asthenopia in North-East India". TNOA Journal of Ophthalmic Science and Research. 55 (3): 182. doi:10.4103/tjosr.tjosr_36_17.
  11. http://journals.lww.com/optvissci/Fulltext/1999/09000/Frequency_of_Convergence_Insufficiency_Among_Fifth.22.aspx
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