Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

OPTHAMOLOGY > Strabismus > Flashcards

Strabismus Flashcards

1
Q

Define strabismus?

What are other names for it?

A

Misalignment of the eyes, whereby one is fixated on the target object and the other has deviated.

Squint
Heterotopia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is:

  • Esotropia
  • Exotropia

What are other names for these two?

A

Inward deviation - convergent squint

Outward deviation - divergent squint - intermittent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Non-paralytic (concomitant) squint:

  • When does it begin?
  • Is there usually a cause?
  • Is it constant or not?
  • Why is it asymptomatic and the patient only notices it when it is pointed out?
  • Does it persist to adulthood?
  • Why is opthalmological assessment needed?
A

Childhood

Usually idiopathic

Can be constant or intermittent

Brain suppresses the image from deviated eye but can cause psychosocial problems for cosmetic reasons

1 in 30 persists

Vision may be damaged it not treated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Non-paralytic (concomitant) squint:

What test is done in the eye exam can be used to diagnose it?

What special test is the gold standard?

What are the 3 O’s of managing this?

A

Corneal reflection test - it is asymmetric in squint

Cover test

Optical
Orthoptic
Operations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Non-paralytic (concomitant) squint:

Management:

Optic - what is done?

Orthoptic - what is done?

Operations - what 2 things can be done?

A

Assessment and correction of any refractive error - helps to realign eyes

Covering good eye encourages use of the bad one

Weakening some muscles by changing their insertion

Strengthening others by resecting them

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Ambylopia:

What is it?

What is a more common name for it?

Why can strabismus cause it?

What else can cause it?

Management

A

Developmental failure of vision in one or both eyes due to visual deprivation.

Lazy eye

Due to prolonged cortical suppression of vision from the deviated

Unequal refractive errors (anisometropia)
Occlusion of one eye (e.g. in congenital cataracts)

Intermittently cover the healthy eye with an eyepatch and cycloplegic drops - corrects refractive error

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Paralytic (incomitant) squint:

Thinking of paralysis of extraocular muscles, what do you think is the cause of this?

What worsens the squint?

How does the squint manifest - what will the patient complain of?

Why do they not get amblyopia?

How is it managed?

A

Cranial nerve 3, 4, or 6 palsy

Brought out or exacerbated on movement

Diplopia

There is no cortical suppression - this could be a way to distinguish them

Self-resolved - only consider surgery if it doesn’t improve after 6-12 months

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Paralytic (incomitant) squint:

3rd (oculomotor) nerve palsy:

  • 3 things that happen?
  • How is it described?
A

Ptosis

Proptosis - same as exophthalmos in Grave’s - due to reduced tone of recti muscles

Down and out

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Paralytic (incomitant) squint:

4th (trochlear) nerve palsy:

  • What muscle is affected?
  • What symptom does the patient get?
  • What can the eye not do?
A

Superior oblique muscle - moves eye in inferiorly

Diplopia

In adduction - eye looks up and cannot look down

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Paralytic (incomitant) squint:

6th (abducens) nerve palsy:

  • What plane is there diplopia?
  • Where does the eye move?
A

Horizontal plane

Moves medially and cannot move laterally as lateral rectus is paralysed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Cranial nerve 3, 4 and 6 lesions:

What extraocular muscles do the horizontal movement? - 2

What does the superior rectus do?

What does the inferior rectus do?

A

Lateral and medial rectus muscle

Looks up and out

Looks down and out

https://www.amboss.com/us/knowledge/Eye_and_orbit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Cranial nerve 3, 4 and 6 lesions:

What do the oblique muscle look towards do?

What muscles do they work with to look straight up or down?

What is an important fact to remember about the direction the superior and inferior obliques move the eye in?

A

They both look towards the nose

What looks down

Inferior/superior rectus

IT IS THE OPPOSITE OF WHAT YOU THINK:
Superior oblique = down
Inferior oblique = up

THEREFORE:
Upward gaze = SR + IO
Downward gaze = IR +SO

https://www.amboss.com/us/knowledge/Eye_and_orbit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Cranial nerve 3, 4 and 6 lesions:

What muscles do the above nerves supply?

A

LR6SO4

CN 3 - Oculomotor:

  • Medial rectus
  • Superior rectus
  • Inferior rectus
  • Inferior oblique

CN 4 - Trochlear - Superior oblique

CN 6 - Abducents - Lateral rectus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Cranial nerve 3, 4 and 6 lesions:

What 2 other things does CN 3 - oculomotor - control?

A

Pupil diameter

Levator palpebrae superioris - lifts the eyelid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Cranial nerve 3 lesions - Causes:

Intrinsic cause do to….? - 1

Extrinsic:

  • What aneurysm in the brain may lead to compression? - - How does this present?
  • What sinister thing could the aneurysm lead to?
  • How can raised ICP cause compression of CN3?
  • What 2 things can cause a cavernous sinus lesion?
A

Ischaemia via DM (microvascular)

Posterior communicating artery aneurysm

Headache - a sign of impending rupture

You can get uncal herniation and CN3 passes just medially to the uncus - https://medical-dictionary.thefreedictionary.com/uncal+herniation

Tumour
Aneurysm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Cranial nerve 4 lesions:

Why is this not relevant?

Cranial nerve 6 lesions:

What is the main cause?

What degenerative disease can also cause lesions?

A

Isolated CN4 lesions are very rare!!!

Raised ICP

MS

17
Q

Presentation of eye problems:

CN 3 lesion - 3 presentations?

What reflexes are reduced? - 2

What can be used to distinguish between compressive causes (e.g. parasympathetic fibres) and intrinsic causes (e.g. ischaemia)?

A

Down and out - SO (down) and LR (out) still working
Ptosis - weakness of upper eyelids
Dilated pupils - controls muscles of pupils

THE PUPILS

Compressive causes mydriasis (dilation of the pupils)
Intrinsic (e.g. ischaemia) - usually pupil sparing

18
Q

Cover-uncover test:

How to manifest squint?

Where will a convergent and divergent squint move to take up fixation?

What does the uncover test detect?

How is the uncover test done?

A

Cover good eye, and see the position of the affected eye

C - Moves medially
D - Moves laterally

Cover an eye for a few seconds
During this time, a covered eye with a latent squint may relax into its deviated position.
So lifting the cover will briefly ‘catch it’ in this position

OPTHAMOLOGY (29 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions