Convergence failure
Convergence insufficiency is a disorder of the two eyes, characterized by a reduced ability of the eyes to turn towards each other or to maintain a convergence position without symptoms. The causes of a weak convergence can be varied and range from sensory-motor disorders of the fusion to neurogenic lesions ( eye muscle paralysis ).
Symptoms
The symptoms and signs associated with convergence insufficiency are often associated with visual activity in the vicinity or near fixation . They may include diplopia (double vision), asthenopia , temporary blurred vision, fatigue, headache, and abnormal posture adjustment , among others .
diagnosis
The diagnosis of convergence failure is made by an orthoptist or an ophthalmologist . Convergence insufficiencies can be accompanied by a sometimes pronounced exophoria , in which the close squint angle is usually greater than the deviation in the distance. A disturbed accommodative convergence / accommodation ratio ( AC / A quotient ), a convergence near point shifted into the distance, reduced fusion breadth and accommodation disorders can also be determined.
therapy
Motor-related convergence insufficiency can be treated with convergence exercises under certain conditions. Some cases of convergence insufficiency are successful eyeglass prescription treatment, including therapeutic prism glasses . It is not uncommon for eye muscle surgery to be the therapy of choice.
research
In 2005, the Convergence Insufficiency Treatment Study (CITT) published two randomized clinical trials. The first study, published in Archives of Ophthalmology, showed that computer exercises combined with office-based vision / orthoptics were more effective than "pencil push-ups" or computer exercises alone for convergence failure in children 9-18 years of age. The second gave similar results for adults between the ages of 19 and 30. In a bibliographical review from 2010, the CITT confirmed its view that office-based accommodation / vergence therapy is the most effective treatment for convergence insufficiency and that it can be replaced in whole or in part by other eye training approaches such as home therapy offer advantages in the Cost, but not the result. A later study from 2012 confirmed that orthoptic exercise resulted in permanent improvement in asthenopic symptoms of convergence sufficiency in both adults and children. A 2011 Cochrane Review confirmed that therapy in the workplace is more effective than therapy at home, although evidence of effectiveness is much stronger for children than for the adult population.
In the fifth and sixth grades, the convergence failure in children is 13%. In studies that used standardized definitions of convergence failure, school and clinic investigators have reported a prevalence of 4.2% to 6%.
See also
literature
- Herbert Kaufmann: Strabismus. 4th fundamentally revised and expanded edition, with Heimo Steffen., Georg Thieme Verlag, Stuttgart, New York 2012, ISBN 3-13-129724-7
