Convergence Insufficiency

What is convergence insufficiency?

Convergence insufficiency (CI) is when the eyes have trouble working together while focusing on an object at that is close by.

With normal vision, your eyes make a series of adjustments to work together to form a single image. When you look from an object that is far away to one that is close, the lens inside your eye slightly changes its shape. The dark part of your eye, the pupil, becomes smaller. Your eyes also move slightly toward the midline in a process called convergence. Your eye and brain carefully coordinate these changes. The result is that you can perceive a single, focused image. When you read, your eyes and brain also have to coordinate the quick, complex eye movements needed to scan a page.

If you have CI, your brain and eye may sometimes have trouble coordinating these changes. One of your eyes may sometimes turn outward instead of converging toward the midline. This makes it hard for your eyes to work together. It can cause blurred vision, double vision, eyestrain, or the need to close one eye when reading.

CI is common. It may be slightly more common in women than in men.

What causes convergence insufficiency?

Researchers are not yet sure what causes CI. There may be problems in the complicated series of actions that the brain and eyes perform. Genes may be partly responsible for CI.

In some cases, a medical condition can contribute to CI. These include:

  • Head injury and concussion
  • Graves disease
  • Myasthenia gravis
  • Parkinson disease
  • Alzheimer disease

Who is at risk of getting convergence insufficiency?

CI tends to run in families. You or your children may be at greater risk for CI if other members of your family have had it.

If you use a computer for long periods, you may also be at greater risk for CI. Other visually demanding jobs might also increase your risk.

You may also be at greater risk for CI if you have certain medical problems.

What are the symptoms of convergence insufficiency?

You are mostly likely to notice symptoms of CI when you do work at a close distance, like reading. Symptoms are even more likely if you do this for an extended period of time. Fatigue also can bring on symptoms. Possible symptoms include:

  • Headache
  • Double vision
  • Eye fatigue
  • Blurred vision
  • Sleepiness when reading
  • Needing to re-read things several times
  • Difficulty concentrating on what you are reading
  • Frequent loss of place when reading
  • Words appear to move, jump, or float on the page
  • Motion sickness or vertigo

Others may notice that one of your eyes sometimes turns outward as you read. (This might happen at the same time you experience blurred vision.) Others also might notice you squinting or closing one of your eyes while you read. (This might make it easier for you to see a single, focused image.)

Symptoms tend to increase during the teens and 20s, but often level off after that.

How is convergence insufficiency diagnosed?

Your eye care professional often begins with a medical history. He or she may ask about symptoms relating to CI.

Your eye care professional will also do a thorough eye exam. This will include testing for visual sharpness. He or she will also test how your eyes converge during tasks that require you to look closely. You may need to repeat this test, using each eye separately and then together. Your eye care professional should be able to diagnose the condition with a medical history and eye exam alone.

An ophthalmologist or optometrist might first diagnose your convergence insufficiency.

How is convergence insufficiency treated?

Eye care professionals often demonstrate and prescribe specific eye exercises to treat CI. You or your child might perform these exercises at home or at the office. Some of these exercises might involve looking through prisms. Computer programs are available that can increase convergence ability and measure improvement over time. Most of the time, symptoms go away after you or your child has regularly practiced the exercises over a relatively short period of time.

Covering one of the eyes does not help correct CI, though it may reduce symptoms temporarily. It doesn’t give you practice working with both eyes together. This is important to correct CI. You may choose to use this method temporarily if you have a lot of close work to perform.

Occasionally, the symptoms of CI do not go away, even with treatment. If that happens, your eye care professional might recommend special prism glasses for reading. These glasses may help you read more comfortably. In very rare cases, your eye care professional might recommend surgery.

Coping with convergence insufficiency

CI may cause your child to have difficulties in school. These children may have difficulty focusing, and they may be slow readers. These problems may go away once they have their CI treated. You should consider a visual exam for any child having difficulty in school.

Exercises to treat CI are very successful for most people. To be effective, it is important to practice these exercises sufficiently. If your child has CI, make sure he or she performs these exercises regularly.

Key points about convergence insufficiency

CI is a common condition in which your eyes have difficulty working together while looking at near objects, such as during reading. One of your eyes may occasionally turn outward instead of converging toward the midline:

  • CI can cause symptoms like blurry vision, double vision, headache, eyestrain, and difficulty reading and concentrating.
  • Symptoms of CI may only happen when you are tired or have a lot of close visual work.
  • Eye care professionals can diagnose CI with a medical history and eye exam.
  • Most of the time, CI will go away if you regularly practice special eye exercises.


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