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15 Cards in this Set
- Front
- Back
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What are the characteristics of convergence insufficiency? |
* Exophoria at near that is greater than exophoria at distance
* Low AC/A ratio * Receded near point of convergence * Reduced fusional vergences |
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What is the AC/A ratio? |
The AC/A ratio is a measure of the amount of convergence for a given amount of accommodation. A high ratio means that the eyes are "over-converging" for a given level of accommodation. A low ratio means that the eyes are not converging enough for a given amount of accommodation. It is a low ratio that is characteristic of convergence insufficiency. A normal ratio is thought to be about 4:1 to 5:1 |
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What are the two methods for measuring the AC/A ratio? |
* Heterophoria method
* Lens gradient method |
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When using the Risley prisms, ____ is used to measure negative fusional vergence. |
Base-in prism |
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A negative fusional vergence measures: |
the ability for the eyes to move apart. |
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A positive fusional vergence measures: |
the ability to bring the eyes together. |
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Use base____ prism to measure PFV. |
base-out |
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Use base ____ prism to measure NFV. |
base-in |
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A small accommodative target is slowly moved toward the eyes until they can no longer converge and they "break" away and diverge. This sentence describes: a. measurement of the AC/A ratio b. measurement of vergence amplitudes c. cover testing d. measuring the near point of convergence |
d. measuring the near point of convergence |
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Clinically, which is not a characteristic of convergence insufficiency? a. exophoria at near that is greater than exophoria at distance b. high AC/A ratio c. receded near point of convergence d. reduced fusional vergences |
b. high AC/A ratio |
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The terms "blur", "break", and "recovery" are used when testing fusional vergence amplitudes. What does the term "recovery" refer to? a.the point at which the eyes feel under stress b.the point at which the eyes are able to again see a single target c.the point at which the eyes see a double image d.the time it takes for the eyes to feel normal again after testing |
b.the point at which the eyes are able to again see a single target |
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What do fusional vergence measurements tell us?
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how well the eyes can maintain fusion when under stress |
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When measuring vergence amplitudes, which measurement should be performed first? a. divergence amplitudes b. convergence amplitudes c. it does not matter which is measured first |
a. divergence amplitudes |
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A "positive fusional vergence test" measures: a. divergence b. convergence c. accommodation |
b. convergence |
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When measuring an exo deviation with the cover test and a prism bar, a ______ is used to measure an exo deviation. a. base-out b. base-in c. base-up d. base-down |
base-in, the prism always points towards the deviation |
