BVP - Strabismus Assessment III - Week 12 Flashcards

1
Q

List the 6 sensory aspects of strabismus.

A

Visual acuity
Fixation
Suppression
Stereopsis
Motor fusion
Anomalous correspondence

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2
Q

Where is fixation on the retina in normal acuity patients? what about with amblyopia (2)?

A

It is central in normal patients - on the macula
In amblyopia, it may be central or unsteady (but around the macula)

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3
Q

Describe eccentric fixation and how it may occur (2). What is the cause?

A

Ocassionally the macula of a deviating eye does not have motor superiority
The fixation is steady by eccentric
The cause is unknown

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4
Q

Can eccentric fixation be seen with casual observation? Explain.

A

Deviation is 1-3 degrees so cant be casually observed

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5
Q

How can the fixation of a patient be assessed? Do these patients (with eccentric fixation) respond to treatment such as occlusion?

A

Use the visuoscope on a direct ophthalmoscope (looks like a sniper scope) to assess the steadiness and centrality of fixation
They do not respond to occlusion

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6
Q

Describe diplopia and confusion in strabismic amblyopia (esotropic eye). Describe using a house and a tree and the patient’s view.

A

Consider a house with a tree on its left, the patient fixates the house, the right eye is esotropic.
The house will fall on the macula in the left eye and nasally on the right eye
Diplopia is seen with the house with one central and another being pereived temporally due to the esotropia
The tree falls on the macula of the esotropic eye and so the central house is superimposed by the tree in their view

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7
Q

List 4 measures of suppression. What degrees of fusion does it measure (2)? What does it assess exactly?

A

Worth 4 dot test
Polarised letters or targets
Red filter ladder
Synoptophore
Measures 1st and 2nd degree fusion
Looks at patients ability to perceive input from the non-dominant eye when both eyes are open

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8
Q

What kind of phenomenon is suppression and what does this mean?

A

Is biocular - both eyes are open

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9
Q

What typically develops when there is diplopia and confusion? What is its primary function?

A

The patient develops a suppression scotoma at least as large as the angle of deviation
Primary function is to remove diplopia and confusion

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10
Q

Can you have amblyopia without suppression? What about suppression without amblyopia?

A

Can have suppression without amblyopia
Cannot have amblyopia without suppression

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11
Q

Is it possible to pass titmus randot with constant strabismus? What about the fly test?

A

Is possible with ~10^D ET for fly test
No patient ever passed titmus randot with constant strabismus

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12
Q

Can a titmus randot test find the following?
Intermittent esotropia
Alternating esotropia
Exotropia

A

Will find both intermittent and alternating esotropia
Will often miss exotropia

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13
Q

Can a titmus randot test find refractive amblyopia?

A

No

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14
Q

At what age can a titmus randot test be performed?

A

Age 3+

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15
Q

Can all children aged 3+ pass titmus fly? What about randot?

A

All should be able to pass the fly test if physiologically able
90% and all 4+ should pass randot

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16
Q

Around what age do children begin to pass all 9 wirt circles?

A

8 to 9

17
Q

Does no stereopsis result in no depth perception? Explain (2).

A

No stereopsis does not result in no depth perception
But does result in reduced depth perception especially up to 3m

18
Q

Define anomalous correspondence.

A

Rearrangement of the correspondence of the receptors of the deviating eye so that it matches the fixating eye
Results in a palse macula over a region not over the macula

19
Q

What is used to test for anomalous correspondence?

A

Bagolini lenses

20
Q

Where is anomalous correspondence thought to occur?

A

It is a ocrtical phenomenon

21
Q

Can anomalous correspondence be central? Explain (2).

A

Yesd and this may cause diplopia following strabismus surgery

22
Q

Describe bagolini glasses and how they assess anomalous correspondence.

A

Like a pair of maddox lenses but are clear and oriented at 56 and 135
Patient looks at a torch while wearing them
If a perfect cross is seen, then no AC, but suppression, imperfect crossing, and missing regions can mean tropia or abnormal correspondence

23
Q

What is the best way to remove anomalous correspondence (2)?

A

Glasses or surgery