Convergence Insufficiency Symptoms and Treatment

Convergence insufficiency is a vision and eye disorder common in children and young adults. This eye muscle disorder makes it difficult for the eyes to turn inward when looking down to read or focus. When attempting to focus on a nearby object, normal eye muscles cause the eyes to converge or turn inward. This allows us to have good fusion and binocular vision so that our eyes maintain one single image. If our eyes do not converge sufficiently, we may have difficulty reading and even experience double vision.

It may not always be evident that someone suffers from convergence insufficiency because the symptoms may vary. People with convergence insufficiency often complain of the following symptoms when reading or doing intense near work:

• Tired eyes
• Headaches
• Moving or overlapping words
• Double vision
• Difficulty concentrating
• Difficulty reading for any length of time
• Squinting or closing one eye

Convergence insufficiency is present in one out of every 20 children. Most likely one to two children in every classroom have this condition. Children with convergence insufficiency are often thought to be lazy or disruptive in the classroom. They tend to have poor attention and often tire more easily when reading.

Diagnosis

Convergence insufficiency is not usually detected on regular vision screenings. Often, the only way it can be properly diagnosed is to see an eye doctor, either an optometrist or ophthalmologist. In fact, pediatric or behavioral vision optometrists or ophthalmologists are better experts in dealing with this condition.

There are several characteristics that eye doctors look for when properly diagnosing convergence insufficiency.

Larger Than Normal Exophoria

First, eye doctors find that a patient suffering from convergence insufficiency has a large exophoria. A phoria is the natural resting position of the eye. In people who suffer from a convergence problem, the natural resting position of eyes is more of an outward position. As a result, not only is that person trying to converge on the near target, but they first have to overcome that larger outward resting position and then converge normally on the target.

Reduced NPC

Second, people who suffer from convergence insufficiency have a reduced near the point of convergence (NPC). NPC is the measurement of how close a fixation target can be brought to the nose while maintaining good binocular vision. A normal NPC can be as little as 1 cm or even all the way to the nose. A person that has a good fusional vergence can keep the target single all the way “to the nose.” An NPC of only 10 cm is considered remote or outside of normal limits. The person cannot bring their eyes inward and maintain good binocular vision at a point more than 10 cm.

Low Binocular Fusional Reserves

Third, people with convergence insufficiency also have low fusional vergence ranges. We normally have a range in which our muscles can diverge or converge our eyes. People with normal vision have quite a large range of which they can move their eyes together quickly to maintain good binocular vision. People with low fusional reserves have no room to compensate. As a result, they cannot converge as much as required. Some people with convergence insufficiency complain of double vision.

Accommodative Insufficiency

Sometimes children and young adults with convergence insufficiency also have accommodative insufficiency. Although you can have one without the other, they often both cause a problem because accommodation and convergence are closely intertwined neurologically. Accommodation is the automatic reflex that occurs when we focus on a near object. The muscle in the eye, as well as the lens, changes to allow increasing focusing power. This allows near objects to become clear. The accommodative system and the convergence system of the eye are closely intertwined and one can affect the other. People with convergence insufficiency often have an inadequate amount of convergence per the amount of accommodation that their eye is doing. They are said to have a low accommodative-convergence/accommodative ratio. Eye doctors can measure this ratio to see if it is outside normal limits.

Treatment

Most eye care professionals treat convergence insufficiency using a home-based therapy called “pencil push-ups.” During pencil push-ups, the patient follows a small letter or picture on a pencil. The pencil is slowly brought toward the bridge of the nose. The goal is to keep the letter clear and single with no double vision. The patient starts off drawing the pencil closer to the nose. Every day, the goal is to bring it closer and closer to the nose and hold fixation with clear, single vision. Pencil push-ups are repeated for 10-15 minutes per day.

Because results of pencil push-ups varied so much, a study was conducted by the National Eye Institute is known as the Convergence Insufficiency Treatment Trial (CITT). This was the first well-designed study comparing the different treatments. The 12-week study compared three forms of vision therapy, two of which were home-based therapy and one office-based therapy performed by a trained therapist. The study found that approximately 75 percent of those who received in-office therapy by a trained therapist plus at-home treatment reported fewer and less severe symptoms related to reading and other near work compared to individuals who had home-based vision therapy alone.

Other Treatments

A special power that moves images is called prism and can be put into an eyeglass prescription. Prism causes the images to be displaced so that a person with convergence insufficiency does not have to converge as much. This does not cure the condition but it does resolve many symptoms. The problem with prism is that some people can adapt to it. As a result, a higher amount of prism must be prescribed to achieve the same effect.

Surgery is usually the last resort for convergence insufficiency since the condition responds so well to vision therapy.

A Word From Verywell

Don’t underestimate the influence that a condition such as convergence insufficiency can have on a child's or young adult’s reading ability, concentration, comprehension, and education. If a child is acting out in class, it could be due to a vision problem such as convergence insufficiency. Parents should know that convergence insufficiency can cause numerous symptoms that make it difficult to read and comprehend. However, doctors now have evidence that office-based vision therapy with a trained therapist plus at-home therapy reinforcement can treat the condition and eliminate symptoms.