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Flashcards in Systemic Disease and Optic Nerve Deck (41):
1

Anatomy of Optic Nerve?

1. How many fibres? Type of nerve fibres? Origin?

2. Where do they synapse? 
3. Where do fibres subserve in Visual Field?

 

  1.  1.2 million afferent nerve fibres
    Originate in the retinal ganglion cells
  2. Most synapse in the lateral geniculate body (some go to the pre-tectalnuclei in the midbrain) 
  3. About 1/3 of the fibres subserve the central 5°of the visual field 

 

2

Describe the optic disk?

1. Shape?

2. Colour?

3. Diameter?

  1. Circular or oval structure
  2. Pale pink.
    The temporal side being slightly lighter than the nasal
  3. ~1.5mm in diameter 

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1. What does optic disc contain? 

2.Describe disc edge? 

  1. The centre has a small depression = physiological cup.
  2.  Disc edges are flat and well defined and the temporal edge is more distinct than the nasal 

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4

  1. What is pigmented arc?
  2. What does it make up of?

  1. It is formed when retina does not reach the optic disc margin
  2. Choroidal pigment 

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5

  1. What artery is in Optic disc? 
  2. What are their branches?

 

  1. The central retinal artery appears on the surface of the optic disc.
  2. It divides into two branches: superior & inferior 

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6

  1. Where do optic nerve fibres become myelinated? 

  1. Lamina cribrosa ( where they exit eyeball) 
    ( Image: paler sheathing, fibres are arcuated) 

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7

Anatomical subdivisions 

  1. How long is the optic nerve between globe to chiasm?
  2. How many segments? How are they subdivided?

  1. 50mm 
  2. 4 segments 
    Intraocular

    Intraorbital

    Intracanallicular

    Intracranial 

     

8

Signs of Optic nerve problems? 
1. VA?

2. Pupil?

3. Colour vision 

4. Sensitivity?

5. Any visual field defects?

 

  1. VA decrease
  2. Afferent pupil defect
  3. Dyschromatopsia

    •Colour vision impairment

    •Mainly affects red or green

    •Quick assessment: ask patient to compare colour of a red object

  4. Diminished light brightness sensitivity

  5. Visual field defects 

9

Underlying disease?

  1.  How to find out underlying disease?
  2. What factors to be considered?

  1. Careful examination & history taking is essential !!!
  2. Consider:
  • Raised ICP
  • Intracranial hypertension:  associated with prescription & non-prescription drugs
  • Ischaemia: Associated with atherosclerosis, diabetes & giant cell arteritis
  • Thyroid disease 

10

Optic Atrophy Signs?

Primary 

  1. Apperance of ONH?
  2. What cause (1)?
  3. Appearance of optic disc? Margin?
  4. Vessels on disc surface?
  5. NFL?

Primary

1. No swelling at ON head

2. Caused by lesions of visual pathway

3. Pale flat disc with clear margins 

4. ↓ # of vessels on disc surface (Kestenbaum sign) with attenuation

5. Thinning of NFL

Secondary

1. Occurs after swelling at ON head

3. White or grey slightly raised disc- Blurry margins

4. Kestenbaum sign 

 

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11

Optic Atrophy Causes?

PRIMARY?

  • Retrobulbar neuritis
  • Compression
    Tumour
    Aneurysm
  • Hereditary neuropathies
  • Other neuropathies
    Toxic
    Nutritional

12

Optic Atrophy Causes 

Secondary?

  • Papilloedema
  • Anterior ischaemic optic neuropathy
  • Papillitis 

13

OPTIC NEURITIS 

  1. What is it?
  2. How is it classified ?

  1. Inflammation , infection or demyelination of optic nerve 
  2. By appearance or aetiology 

14

OPTIC NEURITIS 

Classification? 

 

  1. Retrobulbar neuritis 
  2. Papillitis 
  3. Neuroretinitis 

15

Charateristics of Optic neuritis ?
Describe ONH, Optic disc, RNFL? 

 

  1. Retrobulbarneuritis

    ON head looks normal initially

    Associated with MS

  2. Papillitis
    Affects ON head
    Disc becomes oedematous
    Associated with peripapillaryflame haemorrhage

  3. Neuroretinitis 
    Affects ON head (papillitis)
    RNFL inflammation & macular star
    Least common type of neuritis

     

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16

Differential diagnosis of macular star?
Other disorder causing macular star?

Hypertensive retinopathy

  • Also have cotton wool spots
  • Hard exudate ( due to hypertension) 
  • Some haemorrhage

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17

OPTIC NEURITIS 

Classification by aetilogy?

  1. Demyelinating 
  2. Parainfectious 
  3. Infectious 

18

Optic Neuritis - Demyelinating
Consequences?

Causes?

  • Myelin is lost from nerve fibres
  • Disrupts nervous conduction
  • Can be caused by diseases such as:
    Isolated optic neuritis
    Multiple sclerosis 

19

Optic Neuritis & Multiple Sclerosis 

Associated with any systemic disease clinically?

 

  • Some patients with optic neuritis have no clinically demonstrable associated systemic disease but a close association exists between the two
  • ~ 15-20% of MS patients present with optic neuritis and optic neuritis occurs at some point in 50% of patients with MS 

20

Optic neuritis -demyelinating

  1. Age group
  2. VA? Prognosis of VA?
  3. Signs and Symptoms?

  1. Presentation b/w age of 20 & 50

  2. Monocular VA decrease (6/18-6/60), VA recovers to 6/9 or better in 75% of cases

  3. Phosphenes = white/coloured flashes/sparkles

    Discomfort/pain, especially on ocular movement

    •Afferent pupil defect 

21

Optic neuritis -demyelinating
Visual field defect?

  • Visual field defects are often present
    ↓ sensitivity in central 30°
  • Nerve fibre bundle defects and
    Central scotomas
    Focal defects 

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22

Optic neuritis -parainfectious

  1. Causes? What kind of infections?
  2. When do they occur?
  3. Who are more likely to be affected?
  4. What do patients present with?
  5. Optic disc appearance?

  1. Viral infections: Measles, mumps, chickenpox, rubella, whooping cough and glandular fever
  2. Occur following immunization
  3. Children affected more frequently than adults
  4. Presentation usually 1-3 weeks following a viral infection with acute severe visual loss (can be bilateral) 
    Other neurological features:headache, seizures or ataxia
  5. Papillitis seen at the optic disc or can look normal 

 

 

23

Optic neuritis -infectious
Associate with what kind of infections?
Hint: 6 ! 
S C S L C V

  1. Sinus infection which spreads and puts pressure on the nerve
  2. Cat-scratch fever
  3. Syphilis
  4. Lyme disease (infection from a tick bite)
  5. Cryptococcal meningitis (seen in AIDS patients)
  6. Varicella zoster virus 

 

24

Optic neuritis –non-infectious

  1. Who does it affect?
  2. ON appearance?

  1. Affects about 1-5% of patients with sarcoidosis
  2. Often the optic nerve looks similar to the way it looks with MS 

25

26

OPTIC NEUROPATHIES
Types?

  1. NAION: Non-arteritic anterior ischaemic optic neuropathy
  2. AAION: Arteriticanterior ischaemic optic neuropathy
  3. PION: PAPILLOEDEMA 

27

NAION 

Non-arteritic anterior ischaemic optic neuropathy

  1. Who are prone?
  2. Cause?
  3. Age?

 

  1.  The elderly
  2.  Infarction of the optic nerve head b/c of blockage of the short posterior ciliary arteries
  3.  55 and 70 years 

28

NAION

Non-arteritic anterior ischaemic optic neuropathy
Prediposing factors? ( 5)

 

  1. Hypertension, ↑ cholesterol
  2. Diabetes mellitus, Collagen vascular disease
  3. Sudden hypotensive events, Cataract surgery
  4. Sleep apnoea
  5. Taking “Viagra”

29

NAION

Non-arteritic anterior ischaemic optic neuropathy
Signs, symptoms?

  • sudden, painless, monocular visual loss 
  • vision is reduced upon waking 

30

NAION

Non-arteritic anterior ischaemic optic neuropathy
Clincal Consequences? 

  1. Vision ?
  2. VF defect?
  3. Colour vision loss?
  4. Optic disc?

 

  • ↓ vision ~1/3 of patients will have normal/near normal vision
  • VF defect: Often inferior altitudinal
  • Colour vision loss
  • Swollen optic disc 

Image: 

a. Swollen disc, diffuse oedema 

b. Blurred edge, sectorial haemorrage 

c. haemorrage at Superior nasal sector 

d. leaking blood - lack of perfusion 

 

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31

AAION

Arteriticanterior ischaemic optic neruopathy

  1. Cause?
  2. Present with?
  3. Other signs & symptoms?

 

 

  1. Caused by Giant Cell arteritis
  2. Sudden & severe unilateral visual loss
    periocularpain 
    Possibly flashing lights (photopsia)
  3. Other signs/symptoms
    Jaw claudication
    Headache of recent onset 
    Scalp tenderness
    Weight loss 
    History of polymyalgiarheumatica 

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AAION

Arteriticanterior ischaemic optic neruopathy

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33

NAION vs AAION 

Comparison 

  1. Vision loss ? Sign & Symptoms?

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34

PAPILLOEDEMA 

  1. Optic nerve head appearance?
  2. Causes?
  3. Link to intracranial mass?

  1. Swelling of ONH, secondary to raised intracranial pressure (ICP)
    Usually bilateral, could be asymmetrical 
  2. Other causes of disc oedema in the absence of raised ICP are referred to as 'disc swelling' and usually produce visual impairment. 
  3. All patients with papilloedema should be suspected of having an intracranial mass unless proved otherwise!!! 

35

Papilloedema

  1. Signs? Symptoms?

1. Headache

  • Sudden nausea & vomiting
  • Drowsiness or deterioration of consciousness
  • Transient visual obscurance
  • Horizontal diplopia (c/b CN VI palsy) 

36

Papilloedema 

Stages?

4 stages:

  1. Early
  2. Established
  3. Chronic
  4. Atrophic 

 

37

Papilloedema 

Stage 1- Early

  1. Symptoms? Vision?
  2. Optic disc?
  3. Disc margin? 

  1. No symptoms, normal vision
  2. Mildly elevated discs
  3. Indistinct disc margins initially nasal, later superior, inferior and temporal 

 

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Papilloedema

Stage 2 -Established

  1. Symptoms? Vision? VA?
  2. Optic disc?
  3. Fundus appearance?

 

 

  1. Transient visual obscurations, lasting a few seconds
    VA is normal or reduced
  2. Optic discs elevated with indistinct margins
  3. Venous engorgement, peripapillary flame-shaped haemorrhages and CW spots 

 

 

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39

Papilloedema -Established

  1. Changes in ONH? Cause?
  2. Centre of fovea appearance?
  3. Blind spot?

 

  1. As the swelling increases, the optic nerve head appears enlarged
  2. Hard exudates may radiate from the centre of the fovea in the form of a 'macular fan' -an incomplete star with the temporal part missing
  3. The blind spot is enlarged 

 

 

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40

Papilloedema -Chronic

  1. VA?
  2. VF?
  3. Disc?
  4. Fundus apperance?

 

  1. Variable VA
  2. VF constriction
  3. Elevated discs
  4. No CW spots or haemorrhages 

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41

Papilloedema -Atrophic
1. VA?

2. Optic disc? Colour? Margin?

 

  1. Severe VA impairment
  2. Discs dirty grey in colour
    Elevated
    Indistinct margins 

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