Visual Tracking

Visual Tracking relates to eye movement ability and is also known in the optometric literature as “ocular motility” or “oculomotor function”. In general, this refers to the ability to quickly and accurately look (fixate), visually follow a moving object (pursuit), and efficiently move our eyes so we can fixate on objects from point to point as in reading (saccades). Good visual tracking is essential to proper comprehension of reading material. The eyes have muscles to help move them in the positions that we need as the brain directs that movement. Without the brain understanding where the eyes need to be placed, the brain then starts to adapt the position of the eyes on the page as you will see below.

Signs and Symptoms of visual tracking problems:

  • Frequent loss of place and/or skipping lines while reading
  • Frequent drowsiness or sleepiness following short periods of reading
  • Confusing one word with another as the eyes skip around during reading
  • Habit of using a finger or marker or ruler as an aid during reading
  • Excessive head movement while reading, writing or doing other close work
  • Poor comprehension during reading.
  • Seemingly careless errors during close work
  • Poor reading comprehension
  • Attention and/or behavior problems specifically during reading or other close vision work
  • Headaches when doing close up work such as homework or reading
  • Reading the words backwards either with reading out loud or reading in their head

This is a great animated representation, provided on the Neuro Optometric Rehabilitation Association website, of a visual tracking disorder:

What you're seeing in the above example is the eyes attempting to track the words but not catching all of the words or needing to go back because they missed a word. This kind of tracking leads to the symptoms above. Many patients won't be able to see exactly how they track until they see a Developmental Optometrist who specifically tests for that.

Testing

As explained by Dr. Fortenbacher on the VisionHelp blog, the optometric testing of visual tracking is usually broken down into two general categories: Qualitative chairside observation and Quantitative (measurable) standardized tests. The standard 20-20 eye exam does not test any eye movements, including eye tracking. A person can pass the 20-20 eye exam and still have undetected eye tracking problems.

First, in the category of qualitative chairside observation, the doctor typically uses a fixation target like a pencil, pen, or toy object on the end of a wand and positions it about 8-10 inches in front of the patient’s eyes. The patient is asked to look at and follow the target with their eyes as the doctor moves it horizontally, vertically, and in rotation.

Quantitative tools that optometrists may use to show or measure tracking (and other) disorders include RightEye, the Visagraph, the Readalyzer, the King-Devick Test, and others. These are quick, non-invasive tests that are easy to administer. These tools are getting more sophisticated as technology evolves and research is now showing that eye movement tracking can help diagnose many vision and general health disorders.

Oculomotor Dysfunction

People with visual tracking problems may be diagnosed with Oculomotor Dysfunction. Oculomotor Dysfunction is a common vision problem and occurs in people of all ages, both children and adults. Oculomotor Dysfunction affects reading, sports, balance, depth perception as well as most visually related tasks. Oculomotor Dysfunction is not a condition you can outgrow. Instead, over time, an individual develops compensatory techniques – such as turning of the head while reading, rather than the head remaining stationary while the eyes move across the page of text. In kids, you can see adaptations more easily. For example, in the case of turning the head while reading, the child is literally turning their head left to right in a "no" manner to read the page. This adaptation is extremely time consuming for the child who wishes to read more quickly. This also throws the equilibrium off in the ears as well which could lead to dizziness and headaches. The child might not be able to say why they have a headache which is why it is important for the patient to be seen by a Developmental Optometrist. Any child who has difficulty reading should be seen by a Developmental Optometrist to be evaluated for a possible Oculomotor dysfunction. The sooner Oculomotor dysfunction is caught, the easier it is to keep a child on pace with school.

Treatment of Oculomotor Dysfunction

Treatment for Oculomotor Dysfunction usually includes a treatment program of vision therapy. Vision therapy involves using lenses, prisms, and specific eye and brain activities designed to improve fixation and saccadic eye movements; integrate oculomotor skills with vergence and accommodative systems; integrate oculomotor skills with information processing. Part of your treatment will be to become more aware of your eyes and how they are moving. This awareness helps to control the eyes. Sometimes patients don't know that they have a visual tracking issue and they just feel that their not as "smart" as other people. Conversely, those that have poor reading comprehension due to visual tracking issues often compensate to make up for the poor reading comprehension. Compensation may be that they write excessive notes to remember, highlighting the text, and heavy annotations.

Misdiagnosis

Because the symptoms of a visual tracking disorder are similar to many other disorders, it is commonly misdiagnosed. Unfortunately, even well-trained nurses, pediatricians, teachers, and other professionals fail to consider vision problems when they see children struggling to read, struggling to pay attention, or struggling to progress in school. They can also fail to see fidgeting, anxiety, and behavior problems as signs of undiagnosed vision disorders. These patients are often diagnosed as having Attention Deficit Disorder or Attention Deficit Hyperactive Disorder. Often times, if we can treat the underlying binocular vision disorder, the symptoms of ADD or ADHD will subside. Therefore it is important that school aged children are seen annually for a comprehensive visual assessment with an optometrist that tests binocular vision and visual skills in addition to acuity and general health of the eye.

References

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