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24 Cards in this Set

  • Front
  • Back
What are the 4 types of vergences?
1. Tonic
2. Accomodative
3. Proximal
4. Fusional
What is a pre-requisite for conducting vergences?
What is the definition of Fusional demand?
amount of vergence required to see single (phoria)
What is the definition of fusional reserve?
the amount of vergence remaining after compensating for the phoria
What are different methods of measuring vergences?
-Risley prisms
-Prism bar vergences
-polarized light (vectograms)
-haplascopes (mirrors)
-Anaglyphs (red/green)
True or false: Always test Negative vergences before positive vergences
To test lateral vergences the line of letters should be _____ and to test vertical vergences the LOL should be _____
vertical, horizontal
When measuring lateral vergences you should record what three things?
Blur, break and recovery
When measuring vertical vergences what should you record?
Break and recovery
Why is there no blur in vertical vergences?
B/c accomodation does not help to improve anything
What are the instructions to the patient for measuring lateral vergences?
Tell me IF and When the latters first begin to blur, when they break into two and when they come back together again
Why is there a blur with vertical vergences?
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
T/F: There should be a blur when measuring BI vergences at a distance
False: if the patient is fully corrected than there should be no accomodation to relax out
Which prisms do you use when measuring lateral vergences?
move both prisms uniformly in opposite directions and record the total of both prisms
Which prisms do you use when measuring vertical vergences?
only move one prism and record only the moving prism
When measuring vergences what is the starting point?
the zero mark
What do you record if there is no blur?
What do you record if recovery goes past the zero mark?
EX: -2
What do you record if the patient still sees single after 20^ is reached on each prism?
40+ as the break
What are the expecteds for lateral phorias?
Dist: ortho-2XP

Near: ortho-6XP
What are the expecteds for vertical phorias?
ortho- +/- 0.25^ for both distance and near
What are Morgan's norms?
Phorias: 1X (dist) and 3X (near)
NRV: Dist: x/7/4
Near: 13/21/13
PRV: Dist: 9/19/10
Near: 17/21/11
If a patient says they see a blur when measuring BI vergences what is happening?
The patient has relaxed some accomodation in order to diverge more and keep the image single but is accomodated behind the target (underaccomodated)
If a patient says they see a blur when measuring BO vergences what is happening?
The patient has converged more than the target to keep the image clear and converge some more but now they are overaccomodated