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. 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. 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. Both positive fusional vergence (PFV) and negative fusional vergence (NFV) can be trained, and vergence training should normally include both. 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 one to three months postoperatively. The exophoria at near often recurs after several years, although most patients remain asymptomatic. Reading difficulty In some cases, convergence Insufficiency can be the underlying cause of difficulty learning to read. As a result of the eyes not converging on the same point for sustained periods of time when reading, words can appear blurry or double because the brain is receiving two different images. Convergence insufficiency is not a learning disability. However, some children with the condition who are struggling to learn to read can be confused for having dyslexia due to difficulty learning to read. Children struggling with symptoms such as letters appearing blurry or double and experience tiredness or headaches when reading should consult an optometrist. Prevalence Among fifth and sixth grade children convergence insufficiency is 13%. In studies that used standardized definitions of convergence insufficiency, investigators have reported a prevalence of 4.2–6% 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. See also Amblyopia Strabismus Brock string Ophthalmology Optometry Orthoptics Vision therapy Positive relative accommodation Negative relative accommodation References External links Stereoscopy Disorders of ocular muscles, binocular movement, accommodation and refraction