Brainscape's Knowledge GenomeTM

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


See full index

m4 EYE > Pupillary Abnormalities > Flashcards

Pupillary Abnormalities Flashcards

1
Q

What is pupillary reflex?

A

Shining light in one eye causes constriction of pupils in both eyes. Constriction of pupil in the eye where light in shone is called direct light reflex and constriction of pupil in the fellow eye is called consensual light reflex.

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

Pupillary reflex pathway

A

Afferent pathway
- Light enters pupil and stimulates retina
- Retinal ganglion cells transmit light signal to optic nerve
- Afferent fibres travel along optic nerve from retina to pretectal nucleus in mid brain at the level of superior colliculus
- At the optic chiasm, fibres from nasal retina decussate to optic tract on opposite side and terminate in contralateral pretectal nucleus
- Fibres from the temporal retina remain uncrossed and terminate in ipsilateral pretectal nucleus
- Fibres from optic tracts project and synapse in pretectal nuclei in dorsal midbrain in collicular region
- Each pretectal nucleus is connected with Edinger Westphal nuclei of both sides via internuncial fibres (consensual response)

Efferent pathway
- Edinger-Westphal nucleus projects pre-ganglionic parasympathetic fibres which travel along the oculomotor nerve (CN III) to form the efferent pathway
- Pre-ganglionic fibres travel along the CNIII (inferior division, nerve to inferior oblique) and synapse on post ganglionic parasympathetic vibes in ciliary ganglion
- Post-ganglionic fibres travel via short ciliary nerves to supply the pupillary sphincter causing constriction of pupil and ciliary muscles for accommodation

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

What is consensual pupillary light reflex?

A

Light information given to 1 eye is transmitted equally to both pupils because:
1. Hemidecussation of nasal fibres at optic chiasm
2. Light information received from each pretectal nuclei given to both Edinger-Westphal nuclei

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

What is pupillary near reflex?

A
  • Pupils constrict (miosis) to a near target
  • Near triad
    1. Convergence (in-turning of both eyes)
    2. Accommodation (contraction of ciliary muscles)
    3. Miosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Causes of light near dissociation

A
  1. Adie’s/tonic pupil
  2. Argyll Robertson pupils
  3. Parinaud syndrome
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is Adie’s pupil?

A
  • Lesion is at the ciliary ganglion/ short posterior ciliary nerves
  • Anisocoria worse in light
  • LARGE pupil unreactive to light, reactive when looking at near object
  • Unable to constrict much/sluggish during direct pupillary reflex test
  • Absent deep tendon reflex (Adie’s syndrome)
  • Constricts with 0.1% pilocarpine
  • Vermiform (worm-like) movements of the iris
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Light near dissociation: afferent or efferent problem?

A

Efferent problem

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

What is Argyll Robertson’s pupils?

A
  • Syphilis selectively affects the midbrain (dorsal)
  • Uveitis due to syphilis –> Sticky iris (Iritis) –> Small and irregular pupil
  • Anisocoria worse in light
  • Pupil unreactive to light, reactive when looking at near object
  • Unable to constrict much/sluggish during direct pupillary reflex test
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is parinaud syndrome?

A
  • Lesion in dorsum midbrain where the vertical gaze centre is at, patient will have vertical gaze palsy
  • Accommodation pathway is ventral midbrain whereas pupillary light reflex pathway is dorsal midbrain. Hence, only pupillary light reflex is affected
  • Anisocoria worse in light
  • LARGE pupil unreactive to light, reactive when looking at near object
  • Unable to constrict much/sluggish during direct pupillary reflex test
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Lesions in parinaud syndrome can be caused by

A

Hydrocephalus
Pinealoma
Tumour
AV malformation
Stroke
Multiple sclerosis
Wernicke’s

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

Clinical features of parinaud syndrome

A
  • Supranuclear gaze palsy (Up gaze affected)
  • Lid retraction
  • Convergence-retraction nystagmus (Use optokinetic drum: Patient’s eye will pursuit downwards but saccade upwards = Convergence retraction)
  • Large pupil
  • Light near dissociation
  • Convergence spasm (When patient look up, the eyes converges)
  • Nystagmus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

RAPD: afferent or efferent problem?

A

Afferent problem
- optic nerve problem

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

What are the 2 broad causes of RAPD?

A
  1. Optic neuropathy
  2. Severe macular dysfunction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Causes of optic neuropathy

A
  1. Glaucoma (Most common)
  2. Ischemic Neuropathy (DM/ AION/ NAION)
  3. Demyelinating
  4. Compressive (Tumor - Sphenoid wing/ pituitary/ optic nerve glioma/ meningioma/ thyroid related orbitopathy - large muscle belly/ ICA aneurysm)
    - Lesion at optic tract can lead to differential dilation also
    - Retinoblastoma
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How does light near dissociation occur?

A

Accommodation and pupillary light reflex are separate pathways
Accommodation pathway is ventral midbrain whereas pupillary light reflex pathway is dorsal midbrain

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

Causes of severe macular dysfunction

A
  1. Ischemic CRVO
  2. CRAO
  3. Macular retinal detachment
17
Q

Anisocoria worse in the light means

A
  • Abnormality in the iris sphincter
  • Inability to constrict in pathological eye
  • Dilated pathological pupil
  • LARGE pupil unreactive to light, reactive when looking at near object
  • Parasympathetic problem
  • Unable to constrict much/sluggish during direct pupillary reflex test
18
Q

Causes of anisocoria worse in light

A
  • Adie’s pupil (constricts with 0.1% pilocarpine)
  • Argyll Robertson’s pupil
  • Parinaud pupil
  • Surgical 3rd nerve palsy (constricts with 1% pilocarpine)
  • Pharmacological (no constriction with 1% pilocarpine)
  • Trauma/ Mechanical - Rupture of pupillary sphincter
19
Q

Anisocoria worse in dark means

A
  • Abnormality in the iris dilator
  • Inability to dilate in pathological eye
  • Constricted pathological pupil
  • SMALL pupil unreactive to light, reactive when looking at near object
  • Sympathetic problem
  • Unable to constrict much/sluggish during direct pupillary reflex test
20
Q

Causes of anisocoria worse in the dark

A

Horner’s syndrome
Physiological anisocoria
Sympathetic hypersensitivity

21
Q

Symptoms of Horner’s syndrome

A

Horner’s Syndrome is characterized by
- ipsilateral miosis (constricted pupil) + anisocoria worse in the dark
- partial ptosis
- anhidrosis (in pre-ganglionic cases)

Other symptoms
- Relative enophthalmos
- Heterochromia iridis (seen in congenital cases because the sympathetic innervation is believed to be important for the normal colour development of the iris)

22
Q

Causes of Horner’s syndrome

A
  1. First order neuron
    - Lesion of hypothalamus, brainstem and spinal cord
    - Brainstem stroke: Lateral Medullary Syndrome (LMS)**
    - Demyelination: MS
  2. Second order neuron (pre-ganglionic)
    - Lesions of neck and high thorax
    - Lung apex –> Pancoast tumor**
    - Mediastinum –> Tumour
    - Neck –> Lymphadenectomy, thyroid malignancies
  3. Third order neuron (post-ganglionic)
    - Lesions follow the course of ICA
    - Internal carotid dissection**
    - Cavernous sinus tumour
23
Q

What clinical feature differentiates the level of lesion in Horner’s syndrome?

A

1st order neuron: Ipsilateral anhidrosis of arm and face
2nd order neuron: Ipsilateral anhidrosis of face only
3rd order neuron: NIL anhidrosis

24
Q

Investigations for Horner’s syndrome

A

Step 1: Confirm Horner’s - cocaine test or apraclonidine test
- If the affected eye does NOT dilate → means that there is a horner’s syndrome (clinically significant > 1mm)
- Apraclonidine eye drops reverses anisocoria worse in dark and reverses ptosis

Step 2: Localising lesion
- Hydroxyamphetamine test, phenylephrine test
- Differentiate third from first/second order neuron
- MRI brain, CT neck, angiogram to check for other causes of horner’s

25
Q

Physiological anisocoria

A

Commonest
Pupillary function is normal
Degree of anisocoria remains the same in the light and dark
Not more than 1mm

26
Q

Normal VF extends

A

superiorly 50 degrees
nasally 60 degrees
inferiorly 70 degrees
temporally 90 degrees

m4 EYE (28 decks)

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