This is the concluding part of our vision therapy series and will cover our final major category of disorders that vision therapy is used to treat—Oculomotor Dysfunction.
If you have not read the previous parts of this series, it would be beneficial to do so, as topics discussed previously will not be re-discussed here. In particular, Parts 1 (A Basic Introduction to Vision Therapy) and 2 (The Visual Pathway).
Understanding Oculomotor Dysfunction
Oculomotor dysfunction is a problem in which the eye(s) cannot be controlled properly, moving involuntarily or without certain purpose.
In other words, an individual with oculomotor dysfunction cannot move their eyes as they should. This results in a plethora of problems as our eyes are constantly moving to keep objects single and clear—especially in cases where objects are moving and tracking is required.
Individuals suffering from oculomotor dysfunction often present with symptoms such as:
- Head movement during reading (bobbing of the head, horizontal movement down the line, etc.)
- Skipping lines or losing place easily and frequently during reading
- Decreased reading speed and comprehension
- Difficulty copying information (from the whiteboard, off a presentation, from a book, etc.)
- Poor athletic abilities due to inability to track moving objects (balls, frisbees, moving teammates, etc.)
- Poor depth perception
- Headaches
- Eye strain and fatigue
Children with oculomotor dysfunction often fall behind in class work as it is extremely difficult for them to do schoolwork efficiently. In some cases, children may be misdiagnosed with a learning disorder rather than the actual problem—the eyes.
There are several different aspects of the oculomotor system in which problems can arise—Fixations, Pursuits, and Saccades. An issue with one of these aspects would be classified as an oculomotor deficit, however individuals can have problems with multiple aspects.
Fixation is the skill the allows us to maintain steady fixation upon a given target.
Pursuit is the skill that allows us to maintain steady fixation upon a moving target—pursuits are what allow us to track a ball as it flies toward us, or watch a race car drive around a track.
Saccades are the fastest eye movement the eyes can do and allow us to quickly look at a given target. Examples of saccades include eye movements as you read across a page, looking at your coffee mug and then out the window, and looking quickly to the right or left.
Saccadic dysfunction is the most common type of oculomotor dysfunction, as the eyes can either undershoot (do not move enough to accurately land on the target you choose to look at) or overshoot (move too much to accurately land on the target you choose to look at).
When the eyes do not have accurate saccades, they will need to make correctional movements to get the eyes pointed toward the target at hand. As you can imagine, if this occurs every time you make an eye movement, this could be quite debilitating as the world around you would always appear to be moving.
Diagnosis and Treatment Options for Oculomotor Dysfunction
Diagnosing oculomotor dysfunction involves several different tests and can be tricky to detect. In fact, it often goes misdiagnosed by doctors!
Specialized neuro-optometrists or those specializing in binocular vision disorders are often required to aid with diagnosis and treatment of this group of disorders.
Each aspect of the oculomotor system—fixations, pursuits, and saccades—will need to be evaluated individually and concurrently.
Oculomotor dysfunction treatment can also be quite difficult. Usually, the doctor will start with a pair of prescription glasses and therapy for any accommodative or vergence problems that may be present concurrently.
If this is not sufficient, your doctor may recommend vision therapy.
Vision Therapy Exercises for Oculomotor Dysfunction
If vision therapy is the next step in aiding to relive symptoms induced from oculomotor dysfunction, there are several different exercises that may be utilized.
Hart Chart Saccades Exercise
The objective of this exercise is to improve saccadic eye movement efficiency and accuracy.
One eye is patched—making it a monocular activity. Each eye will be trained individually before being trained together as a way to strength and fine tune each eye’s ability.
This exercise utilizes a special eye chart called a Hart Chart, which is held 5 feet away from the patient. The patient is then asked to read the first letter in the top row of the chart out loud, and then jump down to read the last letter of the chart.
This exercise is repeated with coaching and tips until the individual is able to read two complete columns within 15 seconds without making errors.
Rotatory Peg Board Exercise
The objective of this exercise is to improve accuracy and speed of pursuit movements.
One eye is patched—again making this a monocular activity. This allows for the skill set for each eye to be improved on and equalized between the two eyes before working on their abilities together.
The rotatory peg board is a large rotating board with many small holes in it. The patient is asked to hold a golf tee and push said golf tee into one of the holes in the board. He or she is then asked to track the peg for one full rotation.
This task is repeated, alternating between eyes to improve tracking.
Symbol Tracking
This activity is excellent for simulating tasks that are used in school.
A worksheet is given to the patient with a sequence of letters, numbers, or characters listed at the top.
The rest of the sheet contains a jumbled-up paragraph containing the sequence within. The patient is then asked to scan right to left, from top to bottom, and circle the parts of the master sequence in order, similar to a word search but more specific and created specially to help with oculomotor dysfunction therapy.
Visual Tracing
Visual tracing is similar to a maze or “connect the line” type of worksheet.
Visual tracing therapy worksheets can range in difficulty from easy to difficult depending on the number of distractors on the page.
The patient is asked to follow the line using only his or her eyes from the start point to end point and tell the therapist which line ends where. The patient cannot use a finger to help “keep place”.
Overtime, the worksheets will become harder with the goal of smoother and faster visual tracing.