Convergence Insufficiency

In convergence insufficiency, the eyes cannot be turned inward (converged) sufficiently when looking at nearby objects. While distance vision is unremarkable, one eye drifts outward during near work, such as reading, writing, or screen work. This impairs the coordinated interaction of both eyes and can lead to a variety of complaints.

Difference from exotropia

In exotropia (outward squint), one eye deviates outward both at distance and at near. In convergence insufficiency, on the other hand, the eyes are aligned straight when looking into the distance: the deviation only occurs during near fixation. This distinction is important for choosing the right therapy.

Symptoms

The complaints typically occur during prolonged near work:

• Double vision: occasional or frequent double vision while reading
• Headaches: especially in the forehead area, after reading or screen work
• Eye strain and fatigue: the eyes feel strained and tired
• Difficulty concentrating: especially with schoolwork
• Blurred or "jumping" text: letters appear to move after a longer period of reading
• Blinking or closing one eye: some people unconsciously close one eye in order to read better

Not everyone affected has equally pronounced symptoms. Some have no complaints despite a measurable convergence weakness: in this case no treatment is necessary.

Diagnosis

The diagnosis is made by ophthalmologists or orthoptists. The following parameters are examined:

• Near point of convergence: how close can an object be brought to the nose before one eye drifts off or double vision occurs?
• Fusional vergence range: how much prismatic load can the eyes compensate for before double vision arises?
• Accommodation: the ability to focus the eye is also tested, since it is closely linked to convergence
• Refraction: determination of any refractive error

Treatment

Therapy is only recommended if complaints are actually present. The treatment depends on age, severity of symptoms, and individual needs.

Convergence exercises

Exercises to specifically train eye convergence are considered the most effective therapy. They can be carried out at home or under the guidance of an orthoptist:

• Pencil exercises: a pen is slowly moved toward the nose while trying to keep it in sharp focus with both eyes
• Convergence cards and fusion exercises: special practice cards that train the eyes to converge
• Computer-based training programs: software that improves convergence in a playful way

Prism glasses

Prism glasses can make near work easier by reducing the convergence demand. However, they are usually only used temporarily, since they do not train the actual convergence ability.

What does not help

Covering one eye (patching) is not useful for convergence insufficiency, because it is precisely the interaction of both eyes that needs to be trained.

Surgery

Surgery is only very rarely necessary and is considered only when exercises and prism glasses bring no improvement over a longer period.

Recurrences

In some people, the complaints can recur after illness, lack of sleep, stress, or intensive near work. In such cases, a renewed cycle of exercises can help.

Accompanying vision disorders

Patients with convergence insufficiency may simultaneously suffer from refractive errors or accommodation weakness. These should be recognized and treated, as they can intensify the convergence complaints.

Prognosis

With consistent performance of the convergence exercises, the symptoms improve significantly in most people. Regular check-ups help to verify the success of the therapy and to adjust the treatment if necessary.