We are going to start slowly with one specific topic and break each one down individually. In this post we will be exploring Fixation. As far as a definition for Fixation my favorite (which I pulled in part from the Sanet Volumes) so far is: Definition- The act of directing the eye toward the object of regard causing, in the normal eye, the image of the object to be centered on the fovea. Fixations are a minute scanning motion not observable by the naked eye made up of high frequency tremors, slow drifts and micro saccades. These mini-movements serve to refresh the image on the retina. One of the main reasons I like this definition is because we often think of fixation as keeping the eyes completely still. This is not the case because if our eyes were completely still the image to which we are attending would disappear as it is not being refreshed on the retina. For anyone interested in more information about microsaccades at the right is a great website link (just click on the picture). An example of an optical illusion that is similar to this fading is called Troxler's Effect. To view this you fixate on the red dot for a few moments and you will see the peripheral blue halo disappear. It will reappear upon changing fixation. I often think of fixation as being the underlying foundation for eye movements such as saccades and pursuits. If fixation is inadequate all other following eye movements will be inefficient and inaccurate. Since fixation is the foundation the signs/symptoms of deficient fixation would be much the same as with deficient pursuits/saccades Symptoms/Signs when Deficient-
Therapy- In our office one activity we use early on in therapy to train fixation awareness is called Peripheral Penny Snatch and the activity goes as follows; Peripheral Penny Snatch Purpose: To help the patient improve ability to hold their eyes still while maintaining peripheral awareness. Materials: Pennies, plastic cups Technique: 1. Sit on floor facing patient and put a plastic cup in front of you. 2. Instruct patient to sit facing you, keep their eyes on your eyes and don’t look away. 3. Take a penny in each hand and pinch between your index finger and thumb holding them just past your shoulders to start. 4. Ask the patient to take the pennies from your fingertips without looking away from your eyes. Once the patient has successfully taken the penny from the assistant’s fingertip he/she puts it into the cup while maintaining eye contact. If unsuccessful the patient tries again. 5. Give patient feedback appropriate to performance. For example: “Good, you kept your eyes on mine for a little while, and then you peeked. Let’s try it again…” 6. Repeat while holding the penny at a different starting point each time. 7. Since self-awareness is a goal of vision therapy, when possible, ask patient, “How did you do that time?”, etc. Aspects to be emphasized: 1. Awareness of maintaining eye contact (Did they peek?) and peripheral vision. 2. Patient should have good posture, blink and breathe normally. 3. Patient’s ability to grab pennies accurately. The assignment that goes along with this topic is as follows:
13 Comments
Shannon Sires
10/26/2016 10:15:50 am
A fixation is the ability to aim the fovea at a specific place without any unwanted movement away from the target.
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Michelle Beatty
10/26/2016 11:54:47 am
Great response Shannon! Thanks for being the first to post.
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10/26/2016 07:02:37 pm
Fixations are the resting point between pursuits and saccades. For accurate movement of saccades and pursuits it is important for the patient to be able to fixate. When fixation occurs, the patient is also stimulating the fovea; because of this it is important for patients to be able to fixate quickly.
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Michelle Beatty, COVT
10/26/2016 08:52:28 pm
Nice work Amina! The continuous motion worksheet sounds similar to an activity we use in our office called Number Dotting though the use of circling sounds really interesting.
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10/27/2016 12:58:25 pm
I have not found any specific reasoning regarding the circling of the number the patient is fixated on. However my thought on it is, movement stimulates the periphery the circling may be used to continually stimulate the periphery.
Michelle Beatty
10/27/2016 05:00:04 pm
I actually really like the idea of the circling for the reason you mentioned to stimulate periphery. Great idea!
Lisa Folch
10/26/2016 11:19:20 pm
Fixation is the "direction of the gaze so that the visual image of the object falls on the fovea centralis".
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Shannon Sires
10/27/2016 09:46:16 am
This sounds similar to dive bombing or mega muncher. It's cool to hear the different techniques
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10/27/2016 11:00:01 am
Fantastic work Lisa, I am with Shannon on this one what you describe sounds so much like what we call Dive Bombing in my office. It is so great to be able to hear what other offices do though we are all working on the same skill it is a reminder that there are so many different activities we can use to accomplish the same goal.
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10/27/2016 04:19:10 pm
Fixation is the ability of the eye, specifically the fovea, to point or be aimed at a specific point in space without any deviation.
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Laurie Donnelly
10/31/2016 09:57:20 pm
A fixation is a type of eye movement where the eye is kept aligned with the target for a certain duration of time allowing the image details to be processed. Our perception is guided by alternating the sequence of fixations and saccades.
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Lauren Ginoni
11/1/2016 11:35:36 am
Fixations are the ability to aim the eye(s) at a target and maintain that relative position for 10 seconds or more. These are the foundation of oculomotor control.
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Victoria Marr
11/1/2016 03:14:45 pm
Fixation is the act of directing the eye toward an object of regard, resulting in the image of the object to be centered on the fovea. Small involuntary saccades happen during fixation, which are undetectable by the naked eye. Fixation is an active process where the oculomotor system sends/receives information to/from the brain to keep the image aligned on the fovea.
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