Convergence Insufficiency can produce visual symptoms which also include blurred vision, double-vision, or jumbling and scrambled print as you try to read.

Causes

Convergence insufficiency occurs because of poor eye-teaming ability.  Initially when we view something up close the lines-of-sight from each eye should cross directly where we look at.  A tendency for the eyes to want to drift outward is present in individuals with this disorder.  In order to to keep the image clear and single, more effort is required in order to concentrate on the task.  This ever increasing effort is taxing and soon results in symptoms.  This disorder can run in some families.

Symptoms

Blurred vision at near, eyestrain while doing near work, headaches, sleepiness while reading, double-vision, frequent loss of place when reading,  inaccuracy while checking columns of figures or lists are common complaints.  Severe cases can result in an eye turn.

Diagnosis

A complete and thorough vision exam is required in order to detect this disorder.  During this exam tests must be performed at a near distance in order to measure the eyes tendency to drift and how much ability the eyes have to compensate for this effect.  If not performed this disorder can be missed by the doctor.

Treatment

1. Vision therapy is by and far the most successful treatment available for convergence insufficiency.  The goal of therapy is to build eye teaming ability to a level necessary to overcome the outward drift tendency.

2. Prism incorporated into an eyeglass prescription is a second option.  Success with this form of treatment is much limited than with vision therapy.  Very often adaptation to the new prescription occurs and the convergence insufficiency returns.

3. Alternatives include ocular muscle surgery however most experts do not support this mode of treatment today except in unusual cases.

Video on Convergence Insufficiency

This video reports on results from a study by the National Institutes of Health / National Eye Institute on the treatment of convergence insufficiency.