Convergence Insufficiency

Convergence insufficiency (CI) is a vision condition that causes blurry or double vision and prevents you from focusing on up-close objects. The condition negatively affects reading and concentration. Treatments include eyeglasses, eye exercises, surgery and Botox injections.

What Is Convergence Insufficiency?

While each eye forms an image when you look at an object, you see a single image because your eyes work together to create a single uniform perception.

Sometimes the eyes don’t converge enough when looking at nearby objects. The binocular function is lost as one eye turns outward and the other inward, causing convergence insufficiency (CI).

If you have this eye condition, seek treatment. CI can adversely impact your life. It can cause vision problems such as double or blurred vision, making it difficult to do up-close work.

There are several treatment options for this eye condition.

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Symptoms

You may experience difficulty with near vision when you have convergence insufficiency. Your eyes may struggle to recognize nearby objects or text, causing eyestrain and headaches. 

Signs and symptoms include:

• Sore eyes
• Double/blurred vision
• Difficulty/slow reading
• Concentration problems

When you read, words on a page may seem to float or be out of place, causing you to skip lines or words. Your child may have this eye-coordination problem if you spot them rubbing their eyes, squinting or closing one eye during up-close activities. 

Some people develop convergence insufficiency without symptoms.

Causes

Convergence insufficiency is a malfunction of the muscles that coordinate eye movement for near-vision focusing. Researchers have not identified the cause of the muscular flaw.

Risk Factors

CI doesn’t have a known cause. It occurs more often in people with certain predisposing factors. You may be at a higher risk for this eye condition if you: 

• Have a family history of the vision disorder
• Have a head injury
• Have a brain disease
• Have an autoimmune disorder that damages your eye muscles

Complications

Convergence insufficiency can inhibit reading, but doesn’t necessarily cause of learning disabilities in children. The risk of developing intermittent exotropia is a more serious concern for people with untreated CI. 

With exotropia, eyes are misaligned, with one eye or both turning outward when focusing on something. 

Diagnosis

While 1 in 8 children have CI, the condition often goes undetected in kids that undergo routine eye exams at school. Even adults need more than visual acuity tests to detect the issue.

For a CI diagnosis, see an ophthalmologist or orthoptist if you experience symptoms. Specialists can run the following tests:

• Near point of convergence (NPC) or double vision test. With the NPC test, your doctor asks you to focus on a small object that they hold in front of you. They’ll slowly move the target closer to your eyes until you experience double vision. The doctor will also monitor your eyes for drifting. Your NPC is the distance of the fixation target from your eyes where the outward drift or double vision begins.
• Eye misalignment test. Your doctor can use prism lenses to measure how far outward your eye drifts at near-field focus.
• Refractive error tests. These eye exams can tell if you also have nearsightedness, farsightedness or astigmatism.

Treatment Options

Common CI therapies include:

• Convergence exercises: About 70 percent of CI patients experience better vision with home-based and in-office vision training.
• Software-aided treatment: this involves an interactive program with eye-focusing exercises to improve eye coordination.
• Eyeglasses with built-in prisms: These can help if you have CI with a near or distance vision problem.
• Surgery: Rarely, ophthalmologists perform surgery to treat CI. But it may be necessary if your eye muscles are too weak for the other remedies.
• Botox therapy: A toxin called botulinum can be injected to strengthen eye muscles. You may need multiple injections over time. 

People respond differently to convergence insufficiency treatment. Discuss your unique needs and options with your doctor.

Coping with Convergence Insufficiency

Convergence eye exercises may be a lifelong commitment for some patients. Double vision and eye misalignment can return after successful treatment.

Are There Associated Problems with Vision in Patients with Convergence insufficiency?

Treatment compliance is key to containing your convergence insufficiency. If you don’t treat your condition early, your brain may respond by suppressing vision in one eye.

More serious eye disorders can develop, such as:

• Intermittent exotropia
• Severe loss of binocular vision
• Poor depth perception 

Once you have these vision changes, your hand-eye coordination suffers. Your ability to judge physical distances declines, increasing your risk of trips and falls on stairs or curbs.

Latest Research

While convergence insufficiency can affect any age group, a recent study showed that up to 30 percent of people older than 60 years may have the condition. 

However, there’s some good news for athletes who are unable to return to sports after having had a disabling concussion-induced CI. The National Eye Institute (NEI) is funding research on proper diagnostics and treatment guidelines for this condition to the tune of $3.7 million.

Hopefully, this effort will establish a well-proven standard treatment for convergence deficit after head injury. 

FAQs

Can convergence insufficiency be cured?

Exercises to strengthen convergence can help permanently cure some CI symptoms. However, symptoms can return after discontinuing treatment. 

How do you fix convergence insufficiency?

Effective ways to restore eye coordination in CI patients include:

• Eye exercises to improve convergence
• Surgery or Botox injections to strengthen eye muscles responsible for convergence
• Eyeglasses with built-in prisms, especially for patients with a refractive error like nearsightedness
• Computer-aided eye-focusing exercises

What causes convergence insufficiency?

The condition occurs due to a defect in muscles that coordinate eye movements during up-close work. It’s not clear what causes this defect in most people, but head injuries, genetics, and brain diseases are known risk factors for CI.

References

1. Convergence Insufficiency. (July 2020). Mayo Clinic.

2. Convergence Insufficiency. (May 2021). American Academy of Ophthalmology.

3. Convergence Insufficiency. American Optometric Association.

4. Convergence Insufficiency.(April 2020). Optometrists Network.

5. Convergence Insufficiency. (July 2020). Mayo Clinic.

6. Sustained Improvement of Reading Symptoms Following Botulinum Toxin a Injection for Convergence Insufficiency. (April 2014). Strabismus.

7. Convergence Insufficiency Common in the Geriatric Population. (June 2021). Review of Optometry.

8. An NJIT-Led Team Secures $3.7 Million to Tackle a Disabling, Concussion-Induced Eye Disorder. (September 2021). New Jersey Institute of Technology.