8.1.7

Question 1

What is essential to include in a thorough patient history for incomitant deviations?

Answer 1

Onset, duration, progression of symptoms; presence of diplopia; associated systemic conditions; history of trauma; neurological symptoms

Systemic conditions include diabetes and hypertension.

Question 2

What symptoms may patients report when assessing incomitant deviations?

Answer 2

Diplopia, ptosis, difficulty moving the eye in certain directions

Ptosis refers to drooping eyelid.

Question 3

What does motility assessment evaluate in clinical examination?

Answer 3

Range of eye movements in all directions of gaze

Helps identify limitations and patterns suggestive of specific nerve involvement.

Question 4

What tests can be performed to determine the presence and magnitude of deviations?

Answer 4

Cover-uncover and alternate cover tests

These tests are performed in various gaze positions.

Question 5

Which cranial nerve innervates the superior rectus muscle?

Answer 5

Third Nerve (Oculomotor)

It controls most eye movements and also supplies muscles for eyelid elevation and pupil constriction.

Question 6

What is the role of the Fourth Nerve (Trochlear)?

Answer 6

Innervates the superior oblique muscle, responsible for depression and intorsion of the eye (down and towards the nose)

Important for maintaining head posture.

Question 7

What is the function of the Sixth Nerve (Abducens)?

Answer 7

Innervates the lateral rectus muscle, responsible for abduction of the eye

This muscle allows outward movement of the eye.

Question 8

What are common causes of Third Nerve Palsy?

Answer 8

• Microvascular causes (diabetes, hypertension)
• Aneurysms
• Trauma
• Tumors or lesions

Particularly, posterior communicating artery aneurysms can compress the nerve.

Question 9

What clinical features are associated with Third Nerve Palsy?

Answer 9

• Ocular misalignment (downward and outward deviation)
• Ptosis
• Pupil involvement (dilation, loss of reflex)

If parasympathetic fibers are affected, mydriasis may occur.

Question 10

What diagnostic evaluations are essential for Third Nerve Palsy?

Answer 10

• Neuroimaging (MRI or CT scans)
• Laboratory tests (blood glucose, blood pressure)

Helps identify structural causes and assess microvascular risk factors.

Question 11

What management strategies are recommended for Third Nerve Palsy?

Answer 11

• Address underlying causes (manage diabetes, hypertension)
• Symptomatic relief (prism glasses, ptosis crutches)
• Surgical options (strabismus surgery, eyelid surgery)

Recovery depends on the etiology.

Question 12

What is the prognosis for microvascular Third Nerve Palsy?

Answer 12

Often improves over weeks to months

Traumatic or compressive causes may have variable outcomes.

Question 13

What referral urgency is indicated for acute onset of incomitant deviations?

Answer 13

Urgent referral to rule out life-threatening causes like aneurysms

Especially with pupil involvement.

Question 14

What is the anatomy and function of the Trochlear Nerve (CN IV)?

Answer 14

Exits dorsally from the brainstem, innervates the superior oblique muscle for eye depression and intorsion

It decussates, meaning a right CN IV lesion affects the left eye.

Question 15

What are the clinical features of Fourth Nerve Palsy?

Answer 15

• Vertical diplopia
• Exacerbated when looking down and in
• Compensatory head tilt

Head tilt is towards the opposite side of the palsy.

Question 16

What management options are available for Fourth Nerve Palsy?

Answer 16

• Observe congenital cases
• Fresnel prisms for diplopia
• Surgery if persistent misalignment

Superior Oblique Tuck surgery may be performed.

Question 17

What is the anatomy and function of the Abducens Nerve (CN VI)?

Answer 17

Arises from the pons, innervates the lateral rectus muscle for abduction of the eye

It runs through the cavernous sinus before entering the orbit.

Question 18

What are common causes of Sixth Nerve Palsy?

Answer 18

• Raised intracranial pressure
• Microvascular causes
• Trauma
• Brainstem lesions

Commonly due to tumors or idiopathic intracranial hypertension.

Question 19

What clinical features are associated with Sixth Nerve Palsy?

Answer 19

• Horizontal diplopia
• Esotropia in primary gaze
• Inability to abduct the affected eye

Diplopia worsens when looking towards the affected side.

Question 20

What is the management for microvascular Sixth Nerve Palsy?

Answer 20

Observe, resolves in 3–6 months

Urgent referral needed for high ICP.

Question 21

What condition affects the extraocular muscles in Thyroid Eye Disease?

Answer 21

Graves’ Orbitopathy

Causes swelling of orbital fat and muscles, leading to mechanical restriction.

Question 22

What are clinical features of Duane’s Syndrome?

Answer 22

• Limited or absent abduction
• Adduction limitation
• Upshoot or downshoot on attempted movement
• Narrow palpebral fissure

Involves abnormal development of the abducens nerve.

Question 23

What management options exist for Convergence Insufficiency?

Answer 23

• Vision therapy (orthoptic exercises)
• Prism glasses
• Near-vision exercises

Aimed at improving convergence strength.

Question 24

What may cause horizontal and vertical rectus muscle palsies?

Answer 24

• Trauma
• Neurological disorders
• Mechanical restriction or orbital disease

Examples include stroke or tumors.

Question 25

What is mechanical strabismus?

Answer 25

Results from physical restriction of eye movement ## Footnote Can be due to trauma or orbital disease.

Question 26

What is orbital disease?

Answer 26

Conditions affecting the orbit, including orbital fractures and tumors. ## Footnote Orbital diseases can lead to various visual impairments due to their impact on eye movements and alignment.

Question 27

What is incomitant deviation?

Answer 27

Deviation of the eye that varies depending on which muscle is affected. Eg nerve palsies or muscle dysfunction like mysthenia graves

Question 28

What is diplopia?

Answer 28

Double vision that worsens in certain gaze positions. ## Footnote Diplopia can significantly affect quality of life and may indicate underlying ocular conditions.

Question 29

What are the clinical features of orbital disease?

Answer 29

Incomitant deviation, diplopia, restricted gaze or inability to move the eye in one direction. ## Footnote These features depend on the specific muscles or structures involved.

Question 30

What is the management for orbital disease?

Answer 30

Prism therapy and surgical intervention (strabismus surgery) for significant deviations. ## Footnote Management strategies aim to improve alignment and reduce diplopia.

Question 31

What is mechanical strabismus?

Answer 31

Strabismus resulting from physical restriction of eye movement due to orbital or muscle involvement. ## Footnote This type of strabismus can be due to various anatomical changes or injuries.

Question 32

What are the causes of mechanical strabismus?

Answer 32

* Orbital fractures following trauma * Orbital tumors compressing extraocular muscles * Orbital myositis - inflammatory condition effecting eoms * Fibrosis of the muscle due to previous surgery or trauma ## Footnote Each cause leads to specific clinical manifestations and management strategies.

Question 33

What are the clinical features of mechanical strabismus?

Answer 33

Diplopia with fixed, incomitant deviation and restricted movements in one or more directions of gaze. ## Footnote The degree of restriction depends on the location of the mechanical issue.

Question 34

What is the management for mechanical strabismus?

Answer 34

Surgical treatment to relieve muscle restriction or realign the eyes; prism therapy or glasses may help. ## Footnote The choice of management depends on the severity and cause of the strabismus.

Question 35

What is intermittent exotropia (IXT)?

Answer 35

A condition characterized by intermittent outward deviation of the eye when eye muscles fail to maintain alignment. ## Footnote IXT typically manifests during periods of fatigue or distraction.

Question 36

What are the clinical features of intermittent exotropia?

Answer 36

Intermittent outward deviation, exophoria when eyes are aligned, diplopia when misaligned. ## Footnote These features may vary based on the patient’s state of fatigue or attention.

Question 37

What is the management for intermittent exotropia?

Answer 37

* Prism glasses * Strabismus surgery for realignment * Vision therapy to strengthen convergence ## Footnote Management aims to improve binocular vision and reduce the frequency of outward deviation.

Question 38

What is Duane’s syndrome?

Answer 38

A congenital condition where the abducens nerve fails to develop properly, leading to limited eye movements.

Question 39

What are the three types of Duane’s syndrome?

Answer 39

* Type 1: Limited abduction of the affected eye * Type 2: Limited adduction of the affected eye * Type 3: Limitation in both abduction and adduction

Question 40

Which muscle is primarily affected in Type 1 Duane’s syndrome?

Answer 40

Lateral rectus muscle

Question 41

What is a common clinical feature of Type 1 Duane’s syndrome?

Answer 41

Esotropia (eye turned in when trying to look to the affected side)

Question 42

In Type 2 Duane’s syndrome, which muscle is affected?

Answer 42

Medial rectus muscle

Question 43

What is a common clinical feature of Type 2 Duane’s syndrome?

Answer 43

Exotropia (eye turned outward when attempting to look towards the affected side)

Question 44

What condition is also known as Graves’ Orbitopathy?

Answer 44

Thyroid Eye Disease (TED)

Question 45

Which muscles are commonly affected in Thyroid Eye Disease?

Answer 45

* Inferior rectus * Medial rectus * Superior rectus * Lateral rectus

Question 46

What is proptosis?

Answer 46

Forward displacement of the eye causing bulging eyes.

Question 47

What are common clinical features of Thyroid Eye Disease?

Answer 47

* Restriction in gaze * Diplopia * Proptosis * Periorbital swelling and redness * Abnormal head posture

Question 48

What does the third cranial nerve control?

Answer 48

* Superior rectus * Medial rectus * Inferior rectus * Inferior oblique * Levator palpebrae superioris

Question 49

What is a symptom of third cranial nerve palsy?

Answer 49

Ptosis (drooping of the eyelid)

Question 50

What is the typical eye position in third cranial nerve palsy?

Answer 50

Downward and outward

Question 51

What is the primary muscle affected by the fourth cranial nerve?

Answer 51

Superior oblique muscle

Question 52

What is a common symptom of fourth cranial nerve palsy?

Answer 52

Vertical diplopia

Question 53

What compensatory position might a patient adopt with fourth cranial nerve palsy?

Answer 53

Compensatory head tilt

Question 54

Which muscle does the sixth cranial nerve innervate?

Answer 54

Lateral rectus muscle

Question 55

What is the effect of sixth cranial nerve palsy on eye position?

Answer 55

The affected eye remains turned inward (esotropia)

Question 56

What is a management option for sixth cranial nerve palsy?

Answer 56

Prism glasses to reduce diplopia

Question 57

What are the effects of third nerve palsy?

Answer 57

* Ptosis * Ocular misalignment * Diplopia * Possible pupil dilation (mydriasis)

Question 58

What type of diplopia is associated with sixth nerve palsy?

Answer 58

Horizontal diplopia

Question 59

What is the management approach for fourth cranial nerve palsy?

Answer 59

* Prism correction * Orthoptic exercises * Strabismus surgery in severe cases

Question 60

Fill in the blank: Thyroid Eye Disease primarily affects the _______ muscles.

Answer 60

[extraocular]

Question 61

Fill in the blank: The third cranial nerve is responsible for controlling the _______ muscle.

Answer 61

[most of the eye movements]

Question 62

True or False: The inferior rectus muscle is commonly affected in Thyroid Eye Disease.

Answer 62

True

Question 63

Difference between accommodative and non accommodative tropia

Answer 63

Caused by eyes effort to focus (near triad:accommodation/convergence/pupil constriction) main trigger is hypermetropia as this can overstimulate convergence which can cause eyes to cross - usually esotropia Caused by either congenital or ocular pathology - not linked to accommodation can be any tropia .

Question 64

What is Bielschowsky head tilt test

Answer 64

method used to identify the affected extraocular muscle in cases of vertical diplopia or suspected cranial nerve palsies, especially fourth nerve palsy. It works by analyzing eye movements under different head positions to determine which cyclovertical muscle is underacting.

Question 65

Steps in carrying out Bielschowsky head tilt test

Answer 65

Step 1: Identify the hypertropic eye in primary gaze. • Observe the patient looking straight ahead. • The hypertropic eye is the one where the visual axis is higher, meaning the image from that eye appears lower (due to diplopia). • A right hypertropia means the right eye sits higher, and a left hypertropia means the left eye sits higher. Step 2: Assess the hypertropia during left and right gaze. • Ask the patient to look to the left and then to the right. • If the hypertropia increases in one gaze direction, the affected muscle is likely one that is more active in that gaze. • For example: • If the right hypertropia increases on left gaze, the problem may involve the right superior oblique (SO) or left superior rectus (SR). • If the right hypertropia increases on right gaze, the problem may involve the right inferior rectus (IR) or left inferior oblique (IO). Step 3: Perform the head tilt test. • Tilt the patient’s head toward each shoulder. • When tilting the head toward the affected side, the vertical deviation will increase if the cyclovertical muscle responsible for torsion is impaired. • In fourth nerve palsy (trochlear nerve), tilting the head toward the affected side increases the hypertropia because the superior oblique (which intorts and depresses the eye in adduction) isn’t functioning properly.

Question 66

How to interpret Bielschowsky head tilt test for Right SO palsy

Answer 66

Step 1: In primary gaze, the right eye is hypertropic (right hypertropia). • Step 2: When looking to the left, the right hypertropia increases. • Step 3: When tilting the head to the right, the right hypertropia increases.

Question 67

How to interpret Bielschowsky head tilt test for 3rd nerve palsy

Answer 67

Step 1: In primary gaze, the right eye is hypotropic and exotropic (“down and out”). • Step 2: Hypertropia increases in left gaze due to unopposed left SR. • Step 3: No consistent hypertropia change with head tilt — but ptosis and pupil dilation may be present.

Question 68

How to interpret Bielschowsky head tilt test for 4th nerve palsy

Answer 68

Step 1: In primary gaze, the right eye is hypertropic (right hypertropia). • Step 2: Hypertropia increases in left gaze. • Step 3: Hypertropia increases with right head tilt.