Discovering Vision Therapy Blog

Why Sneaky Convergence Insufficiency is So Difficult to Detect

Posted by Greg Mischio on August 11, 2011

Why sneaky convergence insufficiency is so difficult to detectIf you have convergence insufficiency, you can’t trust your eyes.

Oh they’ll be fine when you look at them in the mirror.  They’ll most likely look like anyone else’s eyes – nicely aligned, pointing at the same object.

But when convergence insufficiency rears its ugly head, those eyes take on a mind of their own.  One of the eyes won’t play fair.  It won’t work with the other eye, and it will drift instead of maintain focus on an object. 

The good news is that convergence insufficiency is not as severe of a vision problem as strabismus and amblyopia.  It is, however, an eye-teaming problem, one that can inhibit the quality of your life if left untreated. And although it isn’t as severe of a vision problem as strabismus and amblyopia, the symptoms can actually be worse.

What is convergence insufficiency?

Convergence insufficiency is a problem with eye ‘teaming.’ Both eyes should point in the same spot and perceive visual space equally in order to work together as a team and provide efficient vision. If you have convergence insufficiency, your eyes will be aligned most of the time, but there may be periods when they aren’t.  Your eyes may drift outward when you’re reading or doing close work, which can result in double vision.  

What causes convergence insufficiency?

Convergence insufficiency is caused by a poorly developed perception of personal visual space.  Good perception of personal visual space is when the things you see and their actual position in space are one in the same. 

What are the symptoms of convergence insufficiency?

You may experience the following symptoms when doing any type of close work, including working on a computer and reading.  The more work you do and the more fatigued you are, the more pronounced the symptoms will become.

  • Eyestrain
  • Headaches
  • Blurred vision
  • Double vision
  • Inability to concentrate
  • Short attention span
  • Frequent loss of place when reading
  • Squinting, rubbing, closing or covering an eye
  • Sleepiness during the activity
  • Trouble remembering what was read
  • Words that appear to move, jump swim or float
  • Problems with motion sickness and/or vertigo


Convergence insufficiency can range from mild eye strain to strain so severe you don’t want to look at an object up close.  More severe cases can experience double vision.

What is convergence excess?

With convergence insufficiency, the eye tends to drift out.  With convergence excess, the eyes tend to point at a spot closer than where the target actually is. For example, if a book is held 16” away from the reader, the eyes may be pointing at a spot only 12” away.  Like convergence insufficiency, this condition results from a poorly developed perception of personal visual space. People with convergence excess have just developed their perception of that space in a different way than someone with convergence insufficiency.

Note that you can have 20/20 eyesight and still have convergence insufficiency or excess.  Tests such as the Snellen Eye Chart and other screenings generally don’t test for eye teaming and space perception, which can reveal convergence insufficiency or excess.

If you have symptoms that match the ones listed above, consider having a Functional Vision Test to determine if you have problems with eye teaming and visual space perception.  It’s the first step to getting those eyes to work together again, and helping to improve your vision.

(Photo by jonycunha)

 The Vision and Learning Guide from The Vision Therapy Center. Learn how undetected vision problems can impact a child's ability to learn.  Download your free Vision and Learning Guide.

Topics: Convergence Insufficiency, Visual Skills