Convergence Insufficiency

Convergence insufficiency (CI) is a common eye muscle coordination problem. When reading or doing close work, a person’s eyes must turn in (converge) for the words to be clear and single. This usually happens easily, without thinking. In CI, the eyes do not turn in easily and as a result, extra convergence effort must be used to force the eyes to turn in. This additional effort can cause a number of symptoms such as eyestrain, headaches, blurred vision, double vision, difficulty concentrating, loss of place and concentration, and reading slowly. CI has no obvious signs and is only detected through an eye examination.

Virtually all people that have convergence insufficiency have 20/20 vision. However, it is not enough to have 20/20 vision and be able to see clearly. For the visual system to function properly we must use our two eyes together in a very precise and coordinated fashion. This ability is referred to as eye teaming or eye coordination. The technical term for this ability is BINOCULAR VISION.

Every time we look at something we must accurately aim the two eyes directly at the object of interest. Each eye sends an image to the part of the brain that is involved in the process of seeing. This part of the brain, called the visual cortex, then attempts to combine these two images to make form one “fused” image. If these images are identical the result is normal, clear, single vision and a perception of depth. If, however, the two eyes are not performing in a coordinated manner the visual cortex will receive two different images and will experience double vision.

here are many types of eye teaming or binocular vision problems. The eyes may tend to drift in, out, up, down, or a combination of these variations. The most common eye teaming problem is convergence insufficiency in which the eyes tend to drift outward when reading or when engaged in any near distance visual activity.

Difficulty converging while engaged in a reading task causes misalignment of the eyes results in double vision unless the individual exerts additional convergence effort to re-align the eyes. As the visual system attempts to eliminate this double vision by using additional convergence effort, a number of significant symptoms can occur. These symptoms, include frequent loss of place, loss of concentration, having to re-read, reading slowly, trouble remembering what was read, sleepiness, blurred vision, diplopia, headaches, and/or eyestrain during reading or other near work.

The Convergence Insufficiency Treatment Trial Investigator Group recently gathered important data about the symptoms of convergence insufficiency in a series of studies (REF). These were the first studies that used a scientifically valid and reliable symptom questionnaire.

These studies found that children with convergence insufficiency reported that the following symptoms occurred “fairly often” or “always” while reading or doing close work:

An interesting finding from these studies was that performance related symptoms (e.g. loss of place, loss of concentration, re-reading the same line, reading slowly, trouble remembering what was read or feeling sleepy) occurred more frequently than eye related symptoms (e.g. blur, headache, diplopia, or asthenopia). This finding is important because it demonstrates that children and adults with convergence insufficiency are likely to experience performance problems when reading.

It is also important to note that the second most common symptom was loss of concentration with almost ½ children reporting this symptom fairly often or always when reading. This potential link between convergence insufficiency and attention disorders has important practical implications for educators, physicians, psychologists other professionals involved in the detection, diagnosis, and treatment of attention deficit hyperactivity disorder. It suggests that a comprehensive vision examination should be mandatory for any child with a suspected attention problem to rule out convergence insufficiency.

To reach a diagnosis of convergence insufficiency the eye doctor must evaluate eye alignment at distance and at near and the ability of the patient to converge as an object is slowly moved towards the eyes. A minimum of three test are required to reach this diagnosis. They include the:

1. Cover test
2. Near point of convergence
3. Convergence amplitude

Cover Test

The doctor used a plastic cover paddle and moves it back and forth from the right to the left eye several times while the patient maintains fixation on a distance and then a near object. The test generally requires less than a minute and allows the doctor to determine if the eyes have a tendency to drift outward.

Near Point of Convergence

The doctor asks the patient to look at a small letter on a stick that looks like a tongue depressor and instructs the patient to keep the letter single as it moves closer and closer to the bridge of the nose. Studies have shown that both children and adults should be able to maintain single vision until the object reaches about 6 cm (≈ 2 inches) from the bridge of the nose). People with convergence insufficiency may report double vision when the letter is significantly further away.

This simple test also requires less than a minute to perform.

Convergence Amplitudes

A measuring device (prism bar) with a series of increasingly stronger prism is held before one eye while the patient tries to keep a small letter single and clear. The doctor slowly increases the magnitude of the prism until the patient reports blurry vision or double vision. This yields a measurement of the patients’ ability to converge the eyes. The patient’s performance can then be compared to well-established expected findings. This test also requires very little time to complete.

Thus, the diagnosis of convergence insufficiency requires simple equipment, a very short period of time and the procedures are well-established and accepted by eye care professionals. It is also important to note that these tests can be performed even with young children who may not be able to accurately report their experiences. The doctor is able to objectively watch the eyes and determine the test results.

Most eye care professionals treat CI using a home-based therapy called “pencil push-ups.” With his eyes, the child follows a small letter on a pencil as the pencil is moved toward the bridge of his nose. His goal is to keep the letter clear and single, but to stop if the letter becomes double. The child is told to try and get the pencil closer and closer each day. Pencil push-ups are practiced for 15 minutes, 5 days per week.

The Convergence Insufficiency Treatment Trial (CITT) was conducted because there was no consensus regarding the most effective treatment for CI. Additionally, a well-designed study had not been conducted comparing the various treatments. The CITT study compared three forms of vision therapy (orthoptics). Two of these were performed at home (home-based therapy) and one was performed in the office (office-based therapy by a trained therapist). The study also included an office-based placebo therapy.

The study was designed as a randomized clinical trial. It included 221 children aged 9 to 17 years who had symptomatic CI. Participants were assigned to 1 of 4 groups:

1. Office-based vergence/accommodative therapy with a trained therapist along with home reinforcement
2. Home-based pencil push-up therapy
3. Home-based computer vergence/accommodative therapy and pencil push-ups
4. Office-based placebo therapy

Nine clinical centers from around the country participated in the study. After 12 weeks of therapy, the children were re-examined by eye care professionals who were unaware of which treatment the children received. Researchers then compared the effectiveness of each of the 3 forms of vision therapy and the placebo therapy option for decreasing symptoms and improving the physical measurements of the convergence problem.

Office-based vergence/accommodative therapy with a trained therapist along with home reinforcement. Children in this group came to the office once per week for a 60-minute therapy session with a trained therapist. During these sessions, the children worked on 4-6 procedures designed to improve the ability to converge the eyes. The children in this group also did home therapy for 15 minutes, 5 days per week to practice the procedures learned during the office visits.

Home-based pencil push-ups therapy. In this group, the child had to follow a small letter on a pencil as the pencil was moved toward the bridge of his nose. His goal was to keep the letter clear and single, but to stop if the letter became double. The child was told to try and get the pencil closer and closer to the bridge of his nose each day. This was practiced for 15 minutes, 5 days per week.

Home-based computer vergence/accommodative therapy and pencil push-ups. In this group, the child was given complex exercises using a computer program plus pencil push-ups.

Office-based placebo therapy. This group was given placebo vision activities designed to simulate office-based therapy.

The 12-week study, known as the Convergence Insufficiency Treatment Trial (CITT), 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. Symptoms of CI include loss of place, loss of concentration, reading slowly, eyestrain, headaches, blurry vision, and double vision.

There are 2 important messages:

1) Parents should know that CI is a common vision problem in school-age children. Children with this problem may experience numerous symptoms that can make it more difficult to read.

2) We now have quality evidence showing that office-based vision therapy with a trained therapist plus at-home reinforcement can effectively treat CI in children 9 to 17 years old. This treatment can improve symptoms and physical measurements of the condition.

The results of this study demonstrate that a 12-week program of office-based therapy by a trained therapist along with additional home reinforcement is more effective than a 12-week program of home-based treatment for CI. The study results apply to children who have symptomatic CI and are aged 9 to 17 years. The CITT will provide eye care professionals with research to assist children who have this condition.

Recent studies that have suggested a possible relationship between CI and Attention Deficit Hyperactivity Disorder (ADHD). Borsting et al10 argued that the symptoms frequently reported in CI such as loss of concentration when reading or reading slowly are similar to behaviors associated with ADHD (inattentive type), such as, failure to complete assignments and trouble concentrating in class.

The authors developed a questionnaire called the Academic Behavior Index (ABS). The Academic Behavior Survey is a 6-item survey that evaluates parent concern about school performance and the parents’ perceptions of the frequency of problem behaviors that their child may exhibit when reading or performing schoolwork (such as: difficulty completing work, avoidance, and inattention). The survey was administered to the parents of 221 children 9-17 years old with symptomatic CI prior to enrolling into the Convergence Insufficiency Treatment Trial and to 49 children with normal vision. The results of this study showed that 15% of the CI group and children with normal vision were classified as ADHD by parental report. An analysis of covariance showed that the total ABS score for the symptomatic CI with parent-report of ADHD group was significantly higher than the symptomatic CI with no parent-report of ADHD group. The authors concluded that both children at risk for ADHD or related learning problems should have a comprehensive vision evaluation to assess the presence of CI as a contributing factor.

1. How often does your child have difficulty completing assignments at school?
2. How often does your child have difficulty completing homework?
3. How often does your child avoid or say he/she does not want to do tasks that require reading or close work?
4. How often does your child fail to give attention to details or make careless mistakes in schoolwork or homework?
5. How often does your child appear inattentive or easily distracted during reading or close work?
6. How often do you worry about your child’s school performance?

Convergence insufficiency is present in 1 out of every 20 children suggesting that in a typical classroom 1-2 children may have this condition. Studies has demonstrated that children with this problem are likely to experience performance related symptoms (e.g. loss of place, loss of concentration, re-reading the same line, reading slowly, trouble remembering what was read or feeling sleepy) as well as eye related symptoms (e.g. blur, headache, diplopia, or asthenopia). In addition, recent studies have found that parents.

In the Convergence Insufficiency Treatment Trial (CITT) we asked parents to complete a survey called the Academic Behavior Index (ABI). The goal was to compare parent responses to a survey assessing behaviors related to school work in children with convergence insufficiency and children with normal eye teaming vision.

The Academic Behavior Index (ABI) is a 6-item survey that evaluates parents’ perceptions of certain behaviors their child may exhibit when reading or performing school-work and parental concern about school performance. Each item is scored from 0 (Never) to 4 (Always) with a total score ranging from 0 to 24. The survey was administered to the parents of 221 children with symptomatic convergence insufficiency prior to enrolling into the Convergence Insufficiency Treatment Trial and 49 children with normal eye teaming.

The results showed that the total ABI survey score for the convergence insufficiency group was significantly higher than for the group of children with normal eye teaming.

The survey items were:

1. Child has difficulty finishing assignments
2. Child has difficulty completing homework
3. Child avoids reading or close work
4. Child makes careless mistakes
5. Child appears inattentive
6. Parent worries about school performance

In summary, parents of children with convergence insufficiency report a higher frequency of behaviors that may interfere with their children’s completion of school work and academic progress. In addition, parents of children with CI reportedly “worry” more about their children’s school performance.