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Clinical Ophthalmology > Neuro 1.3 > Flashcards

Neuro 1.3 Flashcards

1
Q

Causes of a Raised Optic Disc

A
  • Not swollen but very similar appearance
  • Compression
  • Infiltration
  • Congenital optic neuropathies (Leber’s optic neuropathy)
  • Toxic optic neuropathies (methanol poisoning)
  • Traumatic optic neuropathy
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2
Q

Compression

A
  • Orbital masses may compress optic nerve and venous drainage
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3
Q

Compression - Symptoms

A
  • Monocular
  • Slow, compressive visual loss
  • VF loss - may be central or diffuse
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4
Q

Compression - Signs

A
  • Eyelid oedema
  • Proptosis
  • EOM involvement
  • Pupils - RAPD
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5
Q

Compression - Disc Appearance

A
  • If anterior lesion, get disc oedema (will appear oedematous but will be raised)
  • If intraorbital/intracanalicular (further back from ONH), get disc pallor
  • If vasculature not compromised, get ON dysfunction and atrophy despite no preceding disc oedema
  • If BV’s normal, may get dysfunction without raised appearance
  • If swollen or raised, may have simple oedema or visible signs of infiltration
  • Optociliary shunt vessels - smaller vessels that dilate up to try and provide blood supply to affected area
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6
Q

Compression - Management

A
  • Referral for hospital investigations
    • MRI and CT scans conducted if lesion suspected
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7
Q

Compressive Lesion Types

A
  • Optic nerve sheath meningioma
  • Optic nerve glioma
  • Melanocytoma
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8
Q

Optic Nerve Sheath Meningioma

A
  • ON sheath surrounds ON providing it with protection
  • ON sheath meningioma - Benign tumour
  • Proliferation of meningoepithelial cells lining the sheath of the ON
  • One third of ON tumours
  • Mean age - 40-50 yrs
  • More common in females (as are meningiomas elsewhere)
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9
Q

Optic Nerve Sheath Meningioma - Signs and Symptoms

A
  • Painless, slowly progressive monocular visual loss (95% of cases)
  • Proptosis (60-90% of cases)
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10
Q

Optic Nerve Sheath Meningioma - Disc Appearance

A
  • Optic oedema then atrophy (again after 4-6 weeks)
  • Optociliary shunt vessels
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11
Q

Optic Nerve Sheath Meningioma - Management

A
  • Observe if stable and no visual loss
  • Radiotherapy:
    • Stability or improvement in up to 94%
    • Complications:
      • Radiation retinopathy
      • Pituitary dysfunction
  • Surgery:
    • Biopsy or excision
    • Risk of ON trauma and visual loss
    • Considered if intracranial extension
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12
Q

Optic Nerve Glioma

A
  • Optic glioma are usually pilocyctic tumours
  • Most common primary tumour of ON
  • Most are slow growing and benign
  • Some are malignant and more rapidly progressing, causing blindness and death
  • 70% detected during first decade of life, 90% by second
    • Hence less likely if px over 20
  • Association with Neurofibromatosis 1 (NF1):
    • 10-30% of NF1 have optic gliomas
    • 10-70% with optic glioma have NF1
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13
Q

Optic Nerve Glioma - Symptoms

A
  • Proptosis - 94% (main presenting symptom)
  • Visual loss - 87%
  • OD pallor - 59%
  • OD oedema - 35%
  • Strabismus - 27%
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14
Q

Optic Nerve Glioma - Signs

A
  • RAPD
  • VF defect
  • Optociliary shunt vessels
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15
Q

Optic Nerve Glioma - Management

A
  • Observation if good vision and stable imaging appearance
  • Chemotherapy if severe visual loss
  • Radiotherapy has a risk of complications including pituitary dysfunction
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16
Q

Optic Nerve Melanocytoma

A
  • Typically a benign pigmented tumour of uveal tract
  • Composed of melanocytes and melanin, and don’t grow
  • Likes the lamina cribrosa of ONH
  • Rarely become malignant
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17
Q

Optic Nerve Melanocytoma - Presentation

A
  • Can get ON dysfunction if large but usually a coincidental finding
  • Black lesion with feathery edges
  • Typically small and don’t grow
  • Good to monitor with photographs to check if growing
    • Growth (if present) will be very slow
    • Would take pics every 6/12, not every week
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18
Q

Optic Nerve Melanocytoma - Complications

A
  • CRVO
  • Malignant transformation
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19
Q

Optic Nerve Melanocytoma - Management

A
  • Observation every 6-12 months
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20
Q

Infiltration

A
  • Infiltration/invasion of ON by NEOPLASTIC (abnormal growth of cells which replicate - can be benign or malignant replication) or inflammatory cells
  • Ocular involvement may be presenting feature of systemic disease
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21
Q

Infiltration - Symptoms

A
  • Progressive, severe visual loss over days to weeks
  • Associated with headache
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22
Q

Infiltration - Signs

A
  • Retrobulbar infiltration (infiltration behind ONH) - disc appears normal
  • Disc involvement - swollen appearance
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23
Q

Infiltrative Lesions

A
  • Leukaemia
  • Lymphoma
  • Granulomatous infiltration
  • Sarcoidosis, TB, syphilis
  • Metastases
    • Rare but most commonly from breast or lung cancer (can manifest in the eye)
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24
Q

Infiltration - Management

A
  • Urgent referral to ophth

Hospital Investigations:
- MRI of brain and orbits
- CSF analysis
- Screening tests for inflammatory/infective/neoplastic disorders

  • Early identification allows life-saving treatment
  • Palliative care may improve vision if poor prognosis
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25
Inherited Optic Neuropathies - Leber's Hereditary Optic Neuropathy
- Hereditary condition characterised by bilateral optic atrophy - Affects maternal mitochondrial DNA - More common in males aged 10-30
26
Leber's Hereditary Optic Neuropathy - Signs and Symptoms
- Ask about FH - Acute, severe, painless visual loss (<6/60) - Initially monocular but both involved quickly - Central visual loss - RAPD when monocular involvement but NOT when BE affected
27
Leber's Hereditary Optic Neuropathy - Disc Appearance
- Normal in up to 40% - Hyperaemia and elevation of disc - Thickening of peripapillary retina - Peripapillary telangiectasia - Tortuosity of medium sized retinal vessels - Eventual optic atrophy
28
Leber's Hereditary Optic Neuropathy - Management
- MRI scan to exclude a treatable cause - Once diagnosed, there is no treatment and visual loss usually permanent
29
Toxic Optic Neuropathies
- Typical history - alcohol/tobacco excess with neglect of diet (B vitamins & thiamine) - Can get neuropathy in well-nourished individuals with pernicious anaemia (can't metabolise ion properly) or vitamin B12 deficiency Other causes: - Methanol intoxication (component of industrial solvents, antifreeze, fuel) - Amiodarone (treatment of cardiac arrhythmias) - Tamoxifen (prevention and treatment of breast cancer) - Ethalbutamol treatment for TB) - Isoniazid (treatment for TB) - Isotretinoin (treatment for acne)
30
Toxic Optic Neuropathies - Symptoms
- Chronic (gradual & progressive) or acute, depending on the cause - Bilateral and symmetrical - Painless loss of vision - Dimness of vision (like walking into a cloud)
31
Toxic Optic Neuropathy - Signs
- Affects central vision with central scotoma - Minimal findings on initial presentation: - OD can be normal/mild pallor/hyperaemia - In a small group of px's with hyperaemic discs, could get small splinter haemorrhages on disc edge - Mild depression on Amsler fixation target (general dimming) - Reduced CV - Months-years after presentation: - Papillomacular bundle dropout - Temporal disc pallor followed by optic atrophy
32
Toxic Optic Neuropathy - Management
- Investigations of exclusion: - Fluorescein angiography - Blood testing - Electrophysiology - MRI imaging - Reversal of inciting cause (can be difficult - alcohol/tobacco abuse, med subs) - Can get reversal of ocular signs if optic atrophy has not happened - Optic atrophy is a sign of permanent damage, the nerves are damaged and the disc has gone pale, if that hasn’t happened there is potential to reverse the problem
33
Traumatic Optic Neuropathy
- ON damage from trauma to head/orbit/globe - Direct traumatic optic neuropathy - Avulsion of nerve (nerve has dislocated and gone out of its position) from laceration by bone fragments/FB's - Direct compression from haemorrhage (blood from trauma can directly affect ONH) - Indirect traumatic optic neuropathy - something hasn’t physically happened to the nerve/gone into the nerve - Shear forces on nerve (shear force - 2 forces pulling in opposite direction) - Shear forces on vascular supply
34
Traumatic Optic Neuropathy - Examination
- Visual loss - Immediate loss - Severe - no perception of light - RAPD - Optic disc - If pathology is posterior, OD may appear normal - Eventual atrophy - Neuroimaging - Assesses extent of injury and co-morbidity
35
Traumatic Optic Neuropathy - Management
- Neuroimaging to assesses extent of injury and co-morbidity - Prognosis poor - Intravenous steroids - Anti-inflammatory and neuroprotective - Increased risk of mortality when combined with other head injuries - Consider when isolated injury with no other evidence of head injury
36
Causes of APPEARANCE of a Raised Optic Disc
- Optic disc drusen - Tilted optic disc - Myelinated nerve fibres - Hypermetropic crowded disc - Intraocular disease - Central retinal vein occlusion - Posterior uveitis - Posterior scleritis - Hypotony
37
Optic Disc Drusen
- Calcified nodules within ONH - 0.34% - 2% of population - Bilateral in 75% - Unclear pathophysiology - impaired ganglion cell axonal transport (debris from axonal flow deposited in ONH) - Buried in childhood, more prominent with age - Most px's asymptomatic
38
Optic Disc Drusen - Examination
- Possible RAPD if monocular/asymmetric - Visual fields - VF loss in 75-87% - Enlarged blind spot/arcuate defect - Fibres branch from OD to retina, if those fibres were to die, would cause a VF defect along pathway of that fibre (will follow horizontal midline) - Remains stable or very slowly progresses
39
Drusen - Optic Disc
- Appears small in diameter (if drusen pushing things inwards) - Anomalous branching vascular patterns - Round, whitish, yellow refractile bodies - describe in terms of size (in disc diameters, how many) and location (clock like, or nasal/temporal etc) - Disc may be pale/atrophy/RNFL loss
40
Buried Drusen vs Swollen Disc
- Both may elevate the OD and blur its margins - OD drusen does not have: - Lack of hyperaemia - Lack of microvascular changes (telangiectasia etc) - Normal/atrophic nerve fibre layer - Anomalous retinal vascular patterns
41
Tilted Optic Disc
- 1-2% of the population - 80% bilateral - Congenital or associated with myopia (as eye grows in myopia, OD can change and its orientation can tilt) - Oblique insertion of ON - Often the area the disc is tilted away from there is atrophy - Normal vision
42
Tilted Optic Disc - Examination
- Visual field - Bitemporal loss (can be associated with area of atrophy), superior arcuate scotoma
43
Myelinated Nerve FIbres
- 1% of population - Unilateral in 80% - Myelin covers the nerves after they have left the ONH - function of myelin is to speed up the transmission of nerves - During development sometimes the myelin doesn’t stop just behind the ONH and can protrude within the ONH
44
Myelinated Nerve Fibres - Signs and Symptoms
- Usually asymptomatic - Fundus examination - Visible yellow patch of myelin around ONH - Visual fields - Enlarged blind spot corresponding to the area of myelin (covering photoreceptors so light can't get to that area)
45
Hypermetropic Crowded Disc
- Hypermetropic eyes are smaller and have smaller discs - Small discs can make BV's look crowded/dilated and can be misdiagnosed for a swollen or unusual looking disc - BV's just look thicker in comparison to the disc, in reality it is normal
46
Intraocular Disease
- CRVO - Posterior uveitis - Posterior Scleritis - Hypotony
47
Other Optic Neuropathies - Excavated OD anomalies
- OD pit - Coloboma - ON hypoplasia - Morning glory disc syndrome
48
Optic Disc Pit
- Congenital - Depression of disc surface - Associated with VF defect - Serous macular detachment (fluid seeping through hole) - Communication between optic pit and macula - that area of the disc normally contains the fibres which travel to the macula then you can get some fluid in a tunnel where the fibres should have been - Can be liquified vitreous or subarachnoid fluid - That detached area of the retina would have a greyish appearance, normally temporal/inferior to the disc - Associated central vision loss when situated on maculopapular bundle (bit of fibres that takes information back from the macula to the brain)
49
Optic Disc Pit - Management
- Difficult (higher risk as affects macula) - Observe (25% spontaneously resolve, some develop macular involvement) - Argon laser along temporal aspect of disc - Pars plana vitrectomy (take out vitreous if it is the vitreous that is leaking into the pit)
50
Coloboma
- A focal glistening white, bowl-shaped excavation, decentred inferiorly - Congenital defect from incomplete closure of the embryonic fissure (gap left at bottom) - Unilateral or bilateral - Usually occur inferiorly
51
Coloboma - Examination
- Visual acuity - Reduced - Visual Fields - Superior field defect (as is an inferior disc problem) - Can mimic glaucomatous loss (as affecting ONH) - Fundus - Larger than normal OD - Can involve uvea and retina if large
52
Colobomas - Associations
- Microphthalmos (small eye) - Colobomas of iris, choroid and retina
53
Optic Nerve Hypoplasia
- Reduced number of nerve fibres - In isolation (by chance), part of bigger problem with development or associated with: - Midline structures of the brain - Endocrine abnormalities – growth hormone and other pituitary hormones (eye won't grow during development and causes reduced number of nerve fibres and other pituitary hormones) - Suprasellar tumours
54
Optic Nerve Hypoplasia - Predisposing Factors
- Maternal diabetes - Agents ingested by mother during pregnancy including alcohol, LSD, quinine, steroids, diuretics, anticonvulsants, cold remedies etc - Spectrum of severity from asymptomatic to no perception of light depending on how many nerve fibres haven't developed - Unilateral or bilateral
55
Optic Nerve Hypoplasia - Bilateral Cases
- Roving eye movements (not enough nerve fibres - macula not developed properly - poor vision - can't fixate on something - eye will rove side to side looking for clear vision) - Sluggish pupil responses - not many fibres working there and taking info about how much light there is - Less severe bilateral cases: - Squint in one eye - Minor VF defects
56
Optic Nerve Hypoplasia - Unilateral Cases
- Squint in affected eye - RAPD - Unsteady fixation in affected eye
57
Optic Nerve Hypoplasia - Examination
- Visual Fields - Peripheral and arcuate defects (as affects ONH) - Disc appearance - Small diameter of disc (comparison of 2 eyes useful if unilateral) - Grey disc colour and surrounding hypopigmentation - Relatively large retinal BV diameter - Double ring sing is characteristic - white ring of visible sclera *If ratio of, disc diameter: disc-fovea distance > 3:1, likely they have this*
58
Optic Nerve Hypoplasia - Management
- Referral for endocrine opinion - MRI in all cases
59
Morning Glory Disc Anomaly
- Rare congenital malformation, embryonic origin unclear - Funnel-shaped staphylomatous excavation of the ON - Usually unilateral - More common in females
60
Morning Glory Disc Anomaly - Examination
- Visual acuity <6/60 - RAPD - Visual field loss - Fundus - Enlarged disc - Disc pink or orange colour - Chorioretinal pigmentation around excavation (blue/grey pigment coming from the choroid) - White glial tissue on central disc surface - Retinal vessels appear at periphery of disc - Serous retinal detachment

Clinical Ophthalmology (10 decks)

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