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Convergence insufficiency is an eye teaming deficit that affects approximately 8% of people (that is 4 times more prevalent than glaucoma or an eye turn). You do not outgrow convergence insufficiency, which is why it can have lifelong impacts on your vision. Convergence insufficiency can also be caused by a traumatic brain injury (even a concussion). Here is what you need to know about this vision condition that causes headaches, double vision and reading difficulties.

What is convergence insufficiency?

Convergence Insufficiency is described as a common child-hood eye teaming problem, which impacts a child's ability to:

• Work comfortably at near

• Learn to read

• Develop reading fluency

• Demonstrate reading comprehension

• Perform well on timed tests

• Have accurate depth perception

• Achieve athletic potential (especially with ball sports, such as baseball)

Convergence Insufficiency occurs when the two eyes do not maintain proper binocular function during near tasks (when converging one's eyes to look at near material, such as reading). The two eyes do not work as a team, do not focus at exactly the same point while working at near distance (reading, smart phone, tablet, etc). When this happens the individual (child or adult) can experience eyestrain, headaches, double vision (diplopia) or blurred vision. It is not uncommon for the individual to adopt abnormal postures when reading or writing in an effort to obtain a clear, single image.

While convergence insufficiency occurs in many healthy people, it can also be caused by an acquired brain injury. Convergence insufficiency, or convergence palsy, is one of the most common vision conditions resulting from a mild traumatic brain injury. Many people who experience convergence insufficiency following a brain injury often fail to connect their symptoms to a vision condition. While some people will see double, many have vague complaints of headaches, fatigue and balance issues that are actually related to convergence insufficiency.

What does convergence insufficiency look like?

Children and adults with convergence insufficiency are often completely healthy and the structures of their eyes are healthy as well. This is why convergence insufficiency does not show up on a retinal photograph or while reading the eye chart. Convergence insufficiency is a vision problem primarily affecting near visual performance, which is why the eye chart in the distance does little to help identify it.

People with convergence insufficiency can have 20/20 vision and easily pass vision screenings. They can often pass an eye examination if they are not seeing the right type of eye doctor. For this reason, many people with convergence insufficiency remain undiagnosed. This is why it is important for children to see a residency-trained pediatric optometrist for their annual eye exams. A residency-trained pediatric optometrist can diagnose and treat the many vision conditions present in the pediatric population. Individuals of any age who experience symptoms of headaches, eyestrain, double vision or visual fatigue should see an optometrist who is residency-trained in binocular vision and neuro-optometry.

Many of our patients with convergence insufficiency are referred from individuals outside of the eyecare field. Teachers, therapists and parents are often in the best position to see what a patient with convergence insufficiency 'looks like'. There are several symptoms that, if present, warrant a Binocular Vision Assessment to rule out convergence insufficiency. (For a great blog on Binocular Vision Assessments, check out The Eye Wire)

Here are a few of the things you should look for if you suspect convergence insufficiency.

Convergence insufficiency affects how someone sees:

• Text (on paper, tablet, computer or phone) can blur or come in and out of focus. This blurred vision is often intermittent, coming and going with little consistency.

• Words can appear to move, float, jump or swim on the page while reading.

• Double vision, usually intermittent, can be experienced while reading or performing near tasks.

• Letters and words can get 'flipped around' as the child has a hard time looking in the right place at the right time.

Convergence insufficiency affects how someone feels while performing near tasks:

• Headaches, especially in the front of the head or 'behind' the eyes.

• Eyes feel sore, uncomfortable or hurt.

• Eyes (or the person) feels tired or fatigued after a short amount of near work.

• A pulling sensation can be felt around the eyes.

Convergence insufficiency affects how someone acts:

• Individuals with convergence insufficiency will often make attempts to minimize their symptoms. This includes: Covering or closing one eye, leaning on an arm to block an eye, using a finger to keep their place, or asking to be read to (so they don't have to do the visual work of reading).

• Difficulties with reading fluency, often skipping or re-reading lines of text, losing their place or using a finger/line guide to keep their place.

• Challenges with reading comprehension as so much effort is dedicated to keeping things clear and single on the page.

• Difficulties with sight word recognition can often occur as they mistake words with similar beginnings.

• Inconsistent performance – often negatively impacted by timed conditions or fatigue

• Difficulties maintaining concentration.

• Constantly moving around while reading. They are literally trying to find a different way to look at the page as a way to compensate for how they are seeing.

When someone sees what convergence insufficiency looks like, they often have a few different reactions. The first reaction may be 'that sounds like my kid (or me)'. The second is 'this sounds a lot like dyslexia or ADHD'.

The comparison to dyslexia often occurs because both conditions affect a child's ability to read. The confusion may also occur because many people mistake dyslexia (a language-based condition) for convergence insufficiency (a vision-based condition). It is recommended that any child who struggles with reading have both their auditory and visual systems evaluated by the proper professionals.

ADHD occurs at about the same rate as convergence insufficiency, however ADHD seems to be diagnosed as astronomically higher rates. It seems like any child who acts like a kid is at risk for being diagnosed with ADHD. ADHD and convergence insufficiency have many shared symptoms, which is one of many reasons why no condition should be diagnosed based on a subjective symptom survey alone. Fortunately, there are several clinical tests that can objectively diagnose convergence insufficiency (all of which have age-based norms to figure out is your kid just being a kid). It is important to remember that ADHD is the presence of certain symptoms in the absence of a contributing cause. If you suspect ADHD it is recommended that you first rule out a vision (or language) condition first. Ruling our convergence insufficiency is s great first step if your teacher or doctor is talking about ADHD.

Check out our upcoming blog Convergence Insufficiency: Part 2, where we will discuss how convergence insufficiency is diagnosed and treated.