Convergence Insufficiency - All About Vision

Convergence insufficiency (CI) is a condition in which a person’s eyes will gravitate outward when trying to focus on a nearby object. This makes it difficult to read or to focus on materials that are at a close range.

In order to create a single image, the brain implements several adjustments in the eyes to get them to work together. For instance, the lens inside the eye will change depending on whether it’s focusing on a distant object or a close-up one. 

Other adjustments made when near vision is required include pupil constriction and the eyes’ natural tendency to move inward, toward the nose (midline). The inward motion of the eyes is called convergence. 

All of these adjustments are essential for producing sharp up-close vision.  

In cases of CI, there is a disconnect between the brain and the eye when it comes to near vision. The eye may drift outward instead of toward the midline, resulting in eye strain, blurred vision and trouble concentrating on close-up tasks.

Convergence insufficiency is a common condition, affecting 2%-13% of the U.S. population. It is usually seen in adolescents, though adult cases have also been reported. 

It’s important to note that convergence insufficiency is not the same as exotropia, which is a subtype of strabismus (eye misalignment). People with convergence insufficiency only experience eye drifting when focusing up close and can otherwise have good vision. Those with exotropia, meanwhile, will experience eye misalignment constantly or irregularly, regardless of intended focus.

Causes of convergence insufficiency

The cause of convergence insufficiency is not fully understood. It’s suspected that the problem stems from a miscommunication during the brain’s request for near-vision adjustments in the eye. It’s also possible that genetics are partially responsible as the condition tends to run in families.  

In some instances, preexisting conditions that affect the brain can lead to CI. Some of these conditions include:

SEE RELATED: Lazy eye (amblyopia)

Convergence insufficiency  symptoms

Symptoms of convergence insufficiency vary among those affected. In fact, it’s even possible for someone with CI to experience no symptoms at all. 

However, those who do have signs and symptoms of CI will experience them only when using near vision. Common symptoms include:

• Diplopia (double vision).

• Headaches.

• Dizziness.

• Difficulty concentrating on near tasks, including reading — which may cause children to avoid reading or completing school work.

• Eye strain characterized by sore, tired, irritated eyes.

• Squinting, rubbing or closing one eye when focusing up close.