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op3103- bv > 1. Introduction to Orthoptics > Flashcards

1. Introduction to Orthoptics Flashcards

1
Q

What is BSV?

A

It is the ability to use both eyes to contribute to a common single perception.
It allows 1 image to be seen even if you have 2 eyes.

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2
Q

Who can’t have BSV?

A

Uniocular patients- px’s with 1 eye

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3
Q

What is heterotropia (manifest squint)?

A

This is the misalignment of the visual axis. Where 1 eye is either deviated inwards, outwards, up or down. And the other eye is straight.

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4
Q

Heterotropia can alternate between 2 eyes. What does it imply when equal alternation vs alternative squint?

A

Alternative squint- heterotropia alternates between BEs- in eyes with almost equal VA. Unequal RX= one eye will alternate the strabismus.

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5
Q

Why is alternating squint a good sign in children?

A

It suggests that the child is using both visual pathways and they will not develop amblyopia/ lazy eye. Hence, child will not require occlusion therapy.

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6
Q

Microtropia meaning

A

Small angle heterotropia- 10 dioptres or less. here BSV is present even if patient has tropia.

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7
Q

Esotropia meaning?
What is seen with corneal reflex?

A

Deviation of one eye inwards when both eyes are open.
What is seen– reflection on the temporal side of the eye.

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8
Q

Exotropia meaning?
What is seen with the corneal reflex?

A

Deviation of 1 eye outwards.
Corneal reflex seen nasally.

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9
Q

Hypertropia meaning?

A

Deviation of one eye upwards when both eyes are open.

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10
Q

Why do vertical deviations occur?

A

Due to muscle or nerve problems. this is when something is physically stopping the eye from moving. DUE TO MOTILITY DEFECT.

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11
Q

Why are vertical deviations less common compared to horizontal deviations?

A

Vertical fusional range is smaller than horizontal fusional range.
Vertical Range: 18-20^ BO.
Horizontal Range: 35-40^ BO.

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12
Q

What is the meaning of hypotropia?

A

Deviation of one eye downwards when both eyes are open.

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13
Q

How to differentiate between hypotropia vs pseudo ptosis?

A

Difference seen during cover test.
If eye lid moves up during CT- the lid follows the eye suggest the patient has a hypotropia.
Eye lids do not change position with pseudo tropia on the other hand.

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14
Q

What nerve palsy causes droopy eyes and vertical deviation- inability to look upwards?

A

3rd nerve palsy

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15
Q

Cyclotropia- what does the patient complain of?

A

Image tilt with tortional deviation.

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16
Q

4th nerve palsy - what 2 complains?

A

Image tilt and deviation.

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17
Q

Can torsion be managed with prisms?

A

NO
if significant then surgery is required.

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18
Q

Describe heterophoria (latent squint)

A

both eyes are directed towards fixation, eyes are straight ahead normally. However, the eyes deviate upon dissociation- that disrupts fusion.

19
Q

Heterophoria, deviation depends on?

A

Fusional reserves: If insufficient, causes a deviation

20
Q

Define Esophoria

A

The tendency for the eyes to deviate inwards on dissociation.

21
Q

Define exophoria

A

A tendency of the eyes to deviate outwards on dissociation.

22
Q

Define hyper/ hypophoria

A

A tendency for the eyes to deviate up/down on dissociation.

23
Q

Cover/ uncover vs alternating- which one is used to identify a tropia vs phoria?

A

Tropia used to identify with cover/ uncover– uncovered eye is observed.
Alternating CT- covered eye is observed- used to find phoria.

24
Q

What does prism cover test measure?

A

How much the eye moves to take up central fixation.
An objective test
Involves alternating CT & Use of prism to neutralize movement

25
Q

Does poor VA affect prism cover test results?

A

YES
If the deviated eye has poor VA then it will not be able to take central fixation and therefore the movement cannot be measured.
Hence, for such px’s use methods like the Krismksy method.

26
Q

What is the Krimsky method?

A

Looking at corneal reflections and trying to find asymmetry that is corrected with prism.

27
Q

Which direction is prism used for ESO, EXO, HYPER, HYOP deviations?

A

*Eso deviations: prism base out.
*Exo deviations: prism base in.
*Hyper deviations: prism base down in front of the higher eye.
*Hypo deviations: prism base up in front of the lower eye.

28
Q

E(T) meaning?

A

Intermittent Esophoria

29
Q

Abbreviation for Esophoria and Exophoria?

A

*E = Esophoria
*X = Exophoria

30
Q

How are muscle actions scored?

A

*Limitations/ underaction = a score between -1 and -4. The larger the underaction the greater the number.
*Overactions= a score between +1 and +4. Again the larger the number the greater the overaction.
*A full or normal movement is given a score of 0.

31
Q

amblyopia meaning? how is it treated?

A

lazy eye, do not have normal VA- even with corrected refractive error.
Occlusion therapy – ‘patching’

32
Q

Anisometropia meaning?

A

A significant difference in the refractive error between the two eyes (usually defined as 1 dioptre or more). Often results in the development of amblyopia.

33
Q

What is epicanthus?

A

Skin folds between the nose and medial canthi

34
Q

Nystagmus meaning?

A

Involuntary oscillations of the eyeballs. Can be horizontal, vertical or rotary.

35
Q

Stereopsis meaning?

A

The perception of 3D vision brought about by fusing slightly disparate images (one image from the right eye and one from the left eye).

36
Q

Suppression meaning

A

The mental inhibition of visual sensation of one eye in favor of that of the other eye when both eyes are open. It may occur in heterotropia (pathological) or in normal BSV (physiological).
Suppression only develops in visually immature children, i.e. during the plastic period. An individual who acquires strabismus will have diplopia.

37
Q

What is Cyclotropia (Torsional deviation)?

A

Misalignment of one eye around the sagittal axis resulting in a clockwise or anticlockwise rotation of the globe when both eyes are open.

38
Q

Is BSV present in Microtropia px’s?

A

Yes

39
Q

Relationship between BSV & Stereopsis

A

Normal BSV = Normal Stereopsis

40
Q

How are corneal reflections seen in heterotropia?

A

Reflection is opposite to normal position of where the eye should be.

41
Q

Ductions Vs Version- difference?

A

Ductions- Each eye tested individually.
Version- Both eyes tested.

42
Q

Diplopia pathological cause

A

Pathological: Caused by misalignment of the visual axis.

43
Q

How does synoptophore work?

A

2 separate images presented to each eyes, used to diagnose the imbalance of eye muscles, assess angle of deviation and binocular potential.

op3103- bv (11 decks)

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