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24 Cards in this Set
- Front
- Back
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What are the 4 types of vergences?
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1. Tonic
2. Accomodative 3. Proximal 4. Fusional |
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What is a pre-requisite for conducting vergences?
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binoculartiy
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What is the definition of Fusional demand?
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amount of vergence required to see single (phoria)
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What is the definition of fusional reserve?
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the amount of vergence remaining after compensating for the phoria
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What are different methods of measuring vergences?
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-Risley prisms
-Prism bar vergences -polarized light (vectograms) -haplascopes (mirrors) -Anaglyphs (red/green) |
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True or false: Always test Negative vergences before positive vergences
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True
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To test lateral vergences the line of letters should be _____ and to test vertical vergences the LOL should be _____
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vertical, horizontal
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When measuring lateral vergences you should record what three things?
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Blur, break and recovery
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When measuring vertical vergences what should you record?
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Break and recovery
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Why is there no blur in vertical vergences?
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B/c accomodation does not help to improve anything
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What are the instructions to the patient for measuring lateral vergences?
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Tell me IF and When the latters first begin to blur, when they break into two and when they come back together again
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Why is there a blur with vertical vergences?
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In order to keep the image single a little longer the patient will use their accomodation so they are not accomodated to the target anymore and the image blurs
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T/F: There should be a blur when measuring BI vergences at a distance
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False: if the patient is fully corrected than there should be no accomodation to relax out
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Which prisms do you use when measuring lateral vergences?
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move both prisms uniformly in opposite directions and record the total of both prisms
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Which prisms do you use when measuring vertical vergences?
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only move one prism and record only the moving prism
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When measuring vergences what is the starting point?
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the zero mark
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What do you record if there is no blur?
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X
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What do you record if recovery goes past the zero mark?
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EX: -2
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What do you record if the patient still sees single after 20^ is reached on each prism?
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40+ as the break
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What are the expecteds for lateral phorias?
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Dist: ortho-2XP
Near: ortho-6XP |
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What are the expecteds for vertical phorias?
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ortho- +/- 0.25^ for both distance and near
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What are Morgan's norms?
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Phorias: 1X (dist) and 3X (near)
NRV: Dist: x/7/4 Near: 13/21/13 PRV: Dist: 9/19/10 Near: 17/21/11 |
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If a patient says they see a blur when measuring BI vergences what is happening?
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The patient has relaxed some accomodation in order to diverge more and keep the image single but is accomodated behind the target (underaccomodated)
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If a patient says they see a blur when measuring BO vergences what is happening?
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The patient has converged more than the target to keep the image clear and converge some more but now they are overaccomodated
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