Convergence Insufficiency

Convergence insufficiency is a common binocular vision (eye teaming) problem characterized by difficulty or inability to converge (cross) one's eyes. Convergence is an aspect of visual functioning that develops early in life, allowing a child to explore their visual environment and develop stereopsis (3D vision). When a child has convergence insufficiency, he or she has difficulty maintaining single, clear, comfortable binocular vision; especially at near. This form of binocular vision dysfunction results in a number of visual symptoms, including double vision, headaches, eye strain, and difficulties with reading and other near tasks. If left untreated, or improperly treated, convergence insufficiency will persist throughout adulthood. Convergence insufficiency is a sensory and neuromuscular disorder and is not due to muscle weakness, which is why treatment should be designed to modify the visual-neural connections responsible for convergence.

Causes and Types of Convergence Insufficiency

The exact cause of convergence insufficiency remains unknown, however research consistently shows a link between convergence insufficiency and deficits in the slow adaptive vergence system within the brain. People with an otherwise unremarkable birth, developmental, and medical history can have convergence insufficiency. The vast majority of people with convergence insufficiency are healthy, have healthy eyes and see 20/20. This is one of the reasons convergence insufficiency is frequently missed during vision screenings and most eye exams.


While convergence insufficiency is characterized by difficulties converging, or crossing, the eyes there are two sub-types of convergence insufficiency that have distinct causes.



Secondary convergence insufficiency is a difficulty with convergence that is due to deficient accommodation, or eye focusing. Accommodation (eye focusing) and vergence (eye teaming) are two distinct system that are linked at the neurological level. Accommodative convergence is a process where engaging one's eye focusing causes the eyes turn converge, or turn inward. When the accommodative system fails to function properly and one is unable to engage their eye focusing it can result in difficulties with convergence; secondary convergence insufficiency. As the root cause of the convergence difficulties is in fact due to difficulties engaging eye focusing, treatment is directed at addressing the deficient accommodation.



Convergence palsy is a condition caused by an acquired brain injury. Convergence is one of the many visual functions that can be affected following an acquired brain injury. When trauma, stroke, or other neurological insult affects the convergence pathways of the brain the patient will suffer from a convergence palsy, or inability to converge the eyes. This condition results in a number of visual symptoms, headaches, and affects many activities of daily life including driving, reading and mobility. Fortunately this condition is well managed by a neuro-optometrist.

Visual Effects of Convergence Insufficiency

The majority of people who have convergence insufficiency are able to see 20/20 on the eye chart, which is why this common binocular vision condition is often missed during vision screenings and regular eye exams. As convergence insufficiency primary affects visual functioning at near, many of the complaints occur during reading, computer work, and other near tasks.


Convergence insufficiency affects vision in several ways, including:

  • Double Vision, especially with reading or other near work
  • Words move, jump, swim, or appear to float on the page

  • Blurred vision or words appearing to come in and out of focus


Convergence insufficiency causes a number of symptoms, including the feeling that your eyes feel:

  • Headaches

  • Tired

  • Uncomfortable

  • Hurt

  • Sore

  • A “pulling” feeling around your eyes


Convergence insufficiency also has a number of effects on performance of near tasks, including:

  • Loss of concentration when reading

  • Difficulty remembering what has been read

  • Loss of place when reading

  • Mistakenly re-reading the same line of text


Due to the connection between convergence and accommodation (eye focusing), up to 58% of children with convergence insufficiency have accommodative dysfunction, or deficient eye focusing skills. When the eye focusing system is not working properly blurred vision results. Blurred vision due to accommodative dysfunction is often intermittent and varies depending on the visual demands of the task. This is why a child may pass a vision screening one day but complain of blurred vision. Blurred vision due to accommodative dysfunction often occurs during prolonged near tasks, such as reading, and when quickly changing focusing distance, such as when taking notes from the board in school.


A correlation exists between convergence insufficiency and learning & attention issues. Children with ADHD, for example, are three times as likely to have convergence insufficiency. Further research into a potential link between convergence insufficiency, attention, and reading abilities is currently under way. Clinical experience has shown that many children improve reading fluency and even attention following proper treatment of their convergence insufficiency. Simply put, it is much easier to read when the words are not moving on the page, becoming double, and blurring in and out of focus. It is easier to remember what you have read when all of your concentration is not devoted to keeping the words on the page clear and single. Reading is also more enjoyable when you do not have a headache and your eyes do not hurt.


DID YOU KNOW? Many of the symptoms of ADD/ADHD are shared with the symptoms of binocular vision dysfunction.


Binocular vision dysfunction, such as convergence insufficiency and ADD/ADHD are NOT the same and the treatment for these conditions is not the same. It is important to rule out a visual condition, such as convergence insufficiency, when going through the process of diagnosing ADD/ADHD. The results of a Binocular Vision Assessment performed by a residency-trained neuro-optometrist will provide valuable information for the pediatrician and other medical professionals on your child's care team.

Detection of Convergence Insufficiency

Convergence insufficiency is best detected during a Binocular Vision Assessment. During this assessment the doctor will conduct a number of tests that assess visual skills such as eye teaming, tracking, and focusing. These results can then be compared to normative data for same-aged peers and the diagnosis of convergence insufficiency can be made.


DID YOU KNOW? Many doctors do not perform the testing necessary to diagnose convergence insufficiency during a routine eye exam.


Convergence insufficiency is most likely to be detected during a comprehensive eye examination if the doctor performs the necessary testing and has advanced training in pediatric eye care, binocular vision, neuro-optometry, or vision therapy. An eye examination with a residency-trained pediatric optometrist or residency-trained neuro-optometrist is an excellent starting point when determining if convergence insufficiency is present.

Treatment of Convergence Insufficiency

Practitioners use a number of treatment approaches when attempting to treat convergence insufficiency. The treatment approach selected by the doctor often is influenced by their level of training, personal understanding of binocular vision dysfunction and their personal treatment philosophy.


Treatment approaches commonly used for convergence insufficiency include:


DID YOU KNOW? Research has shown in-office vision therapy to be the most effective treatment of convergence insufficiency.


Research has shown that office-based vision therapy is by far the most effective treatment for convergence insufficiency. In studies comparing the various treatment approaches, the office-based vision therapy patients showed significant improvements in symptoms and convergence skills when the patients participating in the other treatments did not. Office-based vision therapy should be the first choice in the treatment of vision therapy as the other treatment approaches are ineffective and delay appropriate treatment. Furthermore, when the visual system is modified without proper instruction and supervision the patient risks embedding poor visual skills and inducing unwanted modifications to the visual system, such as suppression or double vision. It is important that any treatment protocol be performed under the direction of a doctor who has advanced training in binocular vision, neuro-optometry and vision therapy.


DID YOU KNOW? Not all vision therapy programs are the same.


At Advanced Vision Therapy Center we use a research-based treatment approach. Every vision therapy program is performed under the direction of our clinical director, Dr. Ryan Johnson, who received his residency training in binocular vision, neuro-optometry, and vision therapy at the University of California, Berkeley. Unlike vision therapy programs that use group settings and rely on computer programs (which have been shown to be less effective), every vision therapy session is conducted one-on-one with our licensed and trained therapists. This treatment philosophy allows us to have an extremely high success rate and provide more improvement with shorter treatment courses. Attention to detail and a customized treatment plan allows the patient to improve their binocular vision skills during the therapy program and maintain those improvements long after the conclusion of vision therapy without the need for repeat therapy.

Improvement Starts Here

With over 25 years of proven success, you can trust Advanced Vision Therapy Center to provide the care you need.

Our Clinical Director is Idaho's only residency trained optometrist in vision therapy and neuro-optometry and is a Fellow of the American Academy of Optometry.  His residency at University of California, Berkeley means he has the expertise and experience to treat even the most complex cases.

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7960 W. Rifleman Street, #155
Boise , Idaho , 83704 USA
Phone:  208-377-1310
Fax:  208-321-1952