Convergence insufficiency

Symptoms and signs

Symptoms and signs are linked to prolonged near-centered tasks. They may include diplopia, asthenopia, transient blurred vision, difficulty sustaining near-visual function, abnormal fatigue, headache, and abnormal postural adaptation.

Some affected individuals report difficulty making eye contact. Convergence insufficiency can underlie difficulty learning to read, as words may appear blurry or double. It is not a learning disability, but children struggling with symptoms such as blurred or double letters and tiredness or headaches when reading should consult an optometrist.

Diagnosis

Diagnosis is made by an eye care professional skilled in binocular vision dysfunctions, such as an optometrist, ophthalmologist, or orthoptist, to rule out organic disease. Findings include patient symptoms, high exophoria at near, reduced accommodative convergence/accommodation ratio, receded near point of convergence, and low fusional vergence ranges or facility. Accommodative amplitudes should also be measured in symptomatic patients, as some have concurrent accommodative insufficiency.

Treatment

Convergence insufficiency may be treated with convergence exercises prescribed by an eyecare specialist trained in orthoptics or binocular vision anomalies. Some cases are managed with eyeglasses, sometimes with therapeutic prisms. Pencil push-ups therapy is performed at home: the patient brings a pencil slowly to within 2–3 cm of the eye just above the nose for about fifteen minutes per day five times per week, recording the closest distance fusion is maintained after each five minutes.

Computer software may be used at home or in an orthoptist's or vision therapist's office. A weekly 60-minute in-office therapy visit may be prescribed, often with additional in-home therapy. Studies have shown that computer exercises combined with office-based vision therapy or orthoptics were more effective than pencil pushups or computer exercises alone for children and for adults. Office-based accommodative or vergence therapy is considered the most effective treatment; home-based therapy may offer cost advantages but not better outcomes.

Orthoptic exercises led to longstanding improvements of asthenopic symptoms in both adults and children. A Cochrane Review concluded that office-based vergence or accommodative therapy with home reinforcement is more effective than home-based pencil or target push-ups or home-based computer vergence or accommodative therapy for children. In adults, evidence for non-surgical interventions is less clear. Virtual reality-based training has been introduced, but a systematic review could not draw clear conclusions due to the small number of relevant studies.

Prevalence

Among fifth and sixth grade children, convergence insufficiency prevalence is 13%. In studies using standardized definitions (exophoria greater at near than at distance, receded near point of convergence, and reduced convergence amplitudes at near), prevalence is 4.2–6% in school and clinic settings. Convergence insufficiency and other visual dysfunctions occur as a consequence of traumatic brain injury; up to 79% of TBI patients report visual symptoms likely related to CI.