PC - Binocular Vision 2 Vergence - Week 2 Flashcards Preview

OD1 - Integrated Ophthalmic Sciences & Preclinical Optometry > PC - Binocular Vision 2 Vergence - Week 2 > Flashcards

Flashcards in PC - Binocular Vision 2 Vergence - Week 2 Deck (31)
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1
Q

What is the vergence of an eye when it has no EOM innervation?

A

17 beyond parallel

2
Q

What is the tonic vergence of an eye?

A

Parallel or slightly esophoric

3
Q

What is the vergence of an eye in the absence of stimuli (no light)?

A

physiological position of rest.

4
Q

Name 5 tests to measure vergence.

A
Prentice card
Maddox rod
Von graefe
Cover test
Maddox wing
5
Q

True or false

Von graefe is the ideal test for children

A

False

6
Q

Define vergence facility, and how its measured.

A

Speed and accuracy of the vergence system to uptake a convergence or divergence response on demand.
Measured using prism flippers, similar to accommodative facility

7
Q

Name 3 anatomical factors that influence the vergence system.

A

Size
Shape of the globe
Position of EOM insertion

8
Q

Name 3 neurological factors that influence the vergence system.

A

Any lesions affecting innervation of cranial nerve III, IV, and VI.

9
Q

Name 5 general factors that influence the vergence system.

A
Fatigue
Alcohol
Tobacco
Medications
Prisms in glasses
10
Q

Name the 6 types of vergence responses.

A
Fusional
Proximal awareness
Accommodative
Tonic
Voluntary (convergence)
Vergence adaptation
11
Q

Describe tonic vergence.

A

Eyes are 17^ beyond parallel when all innervation to EOMs are cut.
Tonic vergence brings EOMs back to parallel or slightly esophoric.

12
Q

What can be said of tonic vergence?

A

It is the physiological position of rest (in the dark as well).

13
Q

Define vergence posture, and describe 5 means of measuring it.

A
Vergence posture is heterophoria, measured by:
Prentice card
Von Graefe
Maddox rod
Cover test
Maddox wing (antiquated)
14
Q

Name the test to measure vergence range/amplitude.

A

Positive and negative relative convergence

15
Q

Name the test to measure vergence facility.

A

BI and BO flipper challenge

16
Q

Define vergence posture.

A

How accurately the eyes point relative to the visual stimulus location

17
Q

What is the preferred means of measuring vergence posture (heterophoria) in school-age children?

A

Prentice card

18
Q

Which is more repeatable, maddox rod or Von Graefe?

A

Maddox rod

19
Q

True or false

Von Grafe is the preferred method of measuring phoria in children.

A

False

20
Q

What is one advantage of maddox wing above all other tests?

A

It can detect cyclophoria, and is sometimes used when it is suspected.

21
Q

What is the main disadvantage of the maddox wing?

A

Inability to control accommodation.

22
Q

Define vergence amplitude/range.

A

The capacity of the vergence system, and how much it can converge/diverge on demand.

23
Q

Describe how PRC and NRC are carried out (2).

A

Use the prentice card and the diamond for fixation. Use the prism bars, and add more ^D, measuring blur, break, and recovery.
Can also be done using the phoropter head, set to converging, and more prisms added using the risley prism.

24
Q

Are the PRC/NRC tests objective or subjective?

A

Subjective, requiring patient input.

25
Q

Define vergence facility.

A

How quickly and efficiently the vergence system can change to uptake convergence or divergence on demand.

26
Q

Describe the test for measuring vergence facility.

A

Pretince card diamond used for fixation, prism flippers used, BO12^D and BI3^D.

27
Q

What is the normal value for posture/phoria at distance and near?

A

Distance - 1exoP ±1^D

Near - 3exoP ±3^D

28
Q

What is the normal value for PRC at distance and near?

A

Distance - 10/16/10

Near - 10/16/10

29
Q

What is the normal value for NRC at distance and near?

A

Distance - 10/16/10

Near - -/6/4

30
Q

What is the normal value for vergence facility?

A

15 cycles/min

31
Q

Can accommodation and vergence be tested independently?

A

No, they are interlinked, and one cannot be tested without considering the other.

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