How to Spot an Undetected Vision Problem in Your Child

By Dr. Kellye Knueppel

This post is sponsored by The Vision Therapy Center, which has offices in Brookfield, Fond du Lac, and Madison, Wisc. 

School vision screenings and conventional eye exams typically only evaluate visual acuity, or 20/20 eyesight. This is a measure of visual clarity and is tested by having a child read lines of letters on an eye chart.

Although an important measurement, a test like this doesn’t evaluate the skills that comprise what developmental optometrists like myself call functional vision. Unfortunately, this also means that some children may go for years with an undetected vision problem, one that can cause them to struggle with a variety of schoolwork.

If you’re a parent at a loss to explain your child’s schoolwork challenges, consider the following. I’ll first explain more about functional vision, including why it’s integral to a child’s learning, and then share common symptoms that could indicate a functional vision problem.

There’s More to Vision Than You May Realize 

Never heard of functional vision? You’re not alone. In my 25 years as a developmental optometrist, time and again I’ve seen how a child’s undiagnosed functional vision problem can baffle parents, teachers, and other healthcare professionals.

Because they’re not familiar with functional vision, they’re unable to pinpoint why an otherwise normal child is struggling with basic types of schoolwork. And to make matters worse, even if the child has 20/20 vision or wears prescription lenses, this won’t necessarily remedy a functional vision problem.  

Functional vision is how your entire visual system — the eyes, the brain, the visual pathways — works together to help you interact with your environment. More specifically, it includes vision skills such as the following:

Eye teaming

In normal vision, this occurs when both eyes align to focus on the same point in space and work together in a precise and coordinated way. 

Good eye teaming allows for normal depth perception, as well as vision that is comfortable, efficient, and single (as opposed to double). Imagine how difficult it would be to read if, for example, you experienced intermittent double vision.

Eye focusing

This encompasses the ability to see an object clearly and to shift focus between objects at different distances. 

For instance, a child may have difficulty keeping reading material in focus and even experience the text as intermittently or constantly blurry. Or, a child may be able to see the text in a book clearly but have difficulty shifting focus from the book to the whiteboard and then back to the book.

Eye movement

This includes the eyes’ ability to maintain fixation on a moving object through space, to move fixation from one object to another, and to sustain fixation on a stationary object. 

Moving your eyes across this line of text and following a fly ball into a glove both require accurate and efficient eye movements. Maintaining eye contact when someone is talking to you is an example of sustaining fixation on a stationary object.

Symptoms of Functional Vision Problems

For parents, it’s especially important to know that when a child has a problem with skills like those above, it can make reading, writing, spelling, and math much more difficult.

Fortunately, telltale signs of a functional vision problem can be fairly easy to spot — if you know what to look for. Let’s take a look at some of the most common.

Observable traits

Sometimes a functional vision problem in your child can manifest itself in observable ways like these:

  • A turned, or “crossed,” eye
  • Frequent tilting of the head toward one side 
  • Excessive squinting, blinking, and/or closing of one eye
  • Any type of action that suggests one eye is favored over the other 
  • Poor visual/motor skills in play, like trouble catching and/or throwing objects
  • “Clumsy” movements such as frequently bumping into furniture, walls, or other people
  • Reports of blurry vision or double vision

Work skills

When it’s time for schoolwork and related activities, a functional vision problem could be rearing its head when your child does things like: 

  • Repeatedly confuses left and right directions
  • Holds a book or object unusually close to the face
  • Twists or tilts head toward a book or object to favor one eye
  • Frequently loses their place when reading or copying text from the board or a book
  • Has difficulty comprehending and/or remembering what they just read
  • Struggles with remembering, identifying, and drawing geometric shapes
  • Often reverses words when reading
  • Uses finger to read
  • Frequently skips words and/or has to backtrack and re-read words
  • Repeatedly omits small words when reading
  • Has an unusually hard time with handwriting
  • Moves head to follow something instead of just moving the eyes

Physical indications

There can also be physical signs of a functional vision problem, like if your child:  

  • Rubs eyes during or after short periods of reading
  • Complains of burning or itching eyes (which may look red and irritated) 
  • Complains of headaches (especially in area of forehead or temples)
  • Frequently gets nauseous or dizzy and/or seems to get motion sickness easily


Functional vision problems can also affect how your child behaves. Here are some examples: 

  • Exhibits a short attention span
  • Gets nervous, irritable, or quickly fatigued while reading or looking at books, or doing other visually intense near-work
  • Loves to learn by asking questions and having conversations but is not interested in reading
  • Shows signs of emotional or developmental immaturity
  • Gets frustrated easily
  • Doesn’t get along well with others

Special note on ADHD. I’ve seen cases where parents have brought in a child diagnosed with ADHD, only to discover that many (or all) of the child’s symptoms could be attributed to a functional vision problem.

A Vision Quiz Can Be the First Step Toward Detecting a Problem

Functional vision problems — especially if left untreated — can be serious. But the good news is that they can often be helped with optometric vision therapy. 

If your child has any of the above symptoms, it’s by no means a definitive indication of a  functional vision problem. But it’s a good starting point. To take the first step toward diagnosis, I strongly recommend taking The Vision Therapy Center’s free online Vision Quiz.

Click here to take the Vision Quiz.

About the author: Dr. Kellye Knueppel is an award-winning developmental optometrist specializing in vision related learning problems, sports vision, and rehabilitative optometry. She is board certified in vision development as a Fellow of the College of Optometrists in Vision Development. Since opening The Vision Therapy Center in 1995, she has dedicated herself to helping people overcome their visual problems.

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