Optic nerve anomalies and neuropathies Flashcards
what is a optic nerve disease defined as
a disease which involves damage to the retinal ganglion cell axons
list the 4 symptoms of a optic nerve disease
loss of vision - if papillomacula fibres are affected (the axons that originate from the macula)
positive scotoma - constricted loss of visual field
desaturation of colours - particularly red colours and over all colour reduction
decreased brightness perception in affected eye - things appear dimmer (if in one eye then can notice the difference)
what are the 4 clinical signs of optic nerve damage
RAPD - impaired/retarded conduction of the ON in diseased eye
Reduced contrast sensitivity
Visual field defects
Colour vision impairment - reg/green and asymmetrical
list the 4 types of visual fields defects that can occur from optic nerve damage
and what does each one depend on
central
centrocaecal
arcuate
altitudinal
depends where in the optic pathway that the lesion is
how can you detect a colour vision impairment on a patient who has optic nerve damage
by testing colour vision in each eye separately rather than bilaterally
which 4 signs of optic nerve damage can be picked up by careful evaluation of ophthalmoscopy
swelling - total or sectoral
diffuse dropout of RNFL
optic atrophy - 1 months after acute injury to the optic nerve
disc drusen - is not a consequence of optic nerve disease, but if you see a swollen optic disc then you need to exclude the possibility that they might have some disc drusen
what are the 2 classifications of optic nerve anomalies
congenital
or
acquired
list the 7 types of congenital optic nerve anomalies
hypoplasia coloboma optic disc pit tilted disc drusen glial remnants myelinated fibres
list the 4 types of acquired optic nerve anomalies
papilloedema
optic atrophy
optic neuritis
AION
what is optic nerve hypoplasia
how does it look
what 2 causes may it be associated with
the underdevelopment of tissue or organ - subnormal number of axons with normal mesodermal and glial tissue
it is an abnormally small disc and tortuous blood vessels which are not pathological (it is a physiological variant oh hypoplasia)
may be associated with:
parental alcohol
or
parental drug abuse
what type of condition is optic nerve hypoplasia
what symptom is it associated with and under what condition
what other manifestations does it have and name 3 of them
non progressive
non inherited
associated with vision loss - only is papillomacula fibres are affected (i.e. if a subnormal amount of macula axons)
it has other systemic manifestations:
- pituitary and endocrine disorders
- short stature
- agenesis of corpus callosum/septum pellucidum (brain/developmental disorders)
what 2 things can you do for management of optic nerve hypoplasia
if associated with astigmatism - correct refractive errors to avoid amblyopia
refer px if not already been investigated - because may have systemic associations
what is a optic disc coloboma
how does the disc appear to look
what is the inheritance type
incomplete closure of the embryonic fissure - during stages of ocular development
disc is enlarged - with a sharply demarcated white bowl shaped excavation inferiorly
it may extend inferiorly to involve the retina and choroid
sporadic or autosomal dominant inheritance
list the appearance of a optic disc coloboma (4)
- disc is enlarged - with a sharply demarcated white bowl shaped excavation inferiorly where the fissure hasn’t closed
- it may extend inferiorly to involve the retina and choroid - the retina appears thin and translucent because of the incomplete closure
- superior disc is fully developed
- green around the areas of the coloboma = where the incomplete closure is
what is the symptom of a optic disc coloboma
what else may it be associated with
what is the ddx
va may be affected depending on the severity
may be associated with neurological defects
ddx = glaucoma
list 3 things that you will do as management of an optic disc coloboma
as its a congenital abnormality - monitor the visual field defect which they will already have due to the coloboma
ensure no associated glaucomatous changes - so check IOPs
inform the GP and patient - refer routinely if your diagnosis is uncertain i.e. if you think its glaucoma, write your ddx in your referral if your uncertain
list 3 optic disc coloboma complications and which speed of referral is required for each
serous retinal macula detachment - soon referral
progressive visual field loss associated with neural retinal thinning - routine referral to Hes
rhegmatogenous retinal detachment (break in the retina from the coloboma) - urgent referral to Hes
what is a optic disc pit
what appearances can they have
where abouts in the disc is it most commonly found
a crater in the optic disc
round/oval
grey white/yellow
= so could be different sizes and different colours
commonly temporal - but could be anywhere
what does a optic disc pit represent
the herniation of rudimentary neuroectoderm tissue
what are the complications of a optic disc pit
variable VF defects - paracentral arcuate connected to the blind spot
depending on amount of papillomacula bundle fibres affected - px may or may not have VA affected
45% of eyes with optic disc pits develop serous retinal detachments
- fluid from the vitreous cavity OR sub-arachnoid space around the optic nerve
- macula - affected if pit is temporal and the fluid can make its way to the macula
what symptom will occur in a optic disc pit if the fluid from the virtuous cavity or sub-arachnoid space reaches the macula and what should you do if this occurs
from a temporal optic disc
metamorphopsia/distortion in their vision
refer the px soon to the hospital
what is your management of someone with a optic nerve head pit if:
previously investigated
not previously investigated
when should you refer the patient soon
if previously investigated: do not refer - just educate the px on warnings of symptoms of retinal detachment
if not previously investigated: refer routinely - educate the px
refer soon if presenting with recently reduced visual acuity (with and without the metamorphopsia)
what is the cause and appearance of congenital tilted disc syndrome
what else is it associated with
non hereditary
titles disc occurs because instead of optic disc entering the globe straight on, it enters the eye at an angle instead
bilateral
superotemporal disc elevated and inferonasal disc displaced posteriorly
associated with thinning of the inferior RPE and choroid (peripapillary atrophy) = lost neural tissue and myopic astigmatism
what is the complications of titled disc syndrome
bitemporal superior quadrantonopia (as nasal fibres damaged)
as both eyes are affected
chiasmal lesions will respect the midline
what is optic disc drusen
how does it develop
what is the prevalence
hyaline bodies
- partly calcified
- maybe has axonal debris
it is present at birth, but starts to manifest in the patient by the time they get to 6 years old at the margins/borders of the optic disc
but it starts off at the deep layers of the retina and then migrates there
as the patient gets older, the drusen gets more calcified
0.3-1.0% of the population
70% bilateral
what is the ddx if optic disc drusen
what should you look for to rule this ddx out
what is the management of optic disc drusen
papilloedema
- as the disc margins are ill defined
but papilloedema is also associated with cotton wool spots and haemorrhages
look for swelling and elevation of disc margins
- vessel engorgement
refer urgently if diagnosis is uncertain
what is a glial remnant of the optic disc
what will it look like and how can it be seen
remnant of the hyaloid artery = birdsmeisters papilla
a white sheath will be floating in the vitreous best seen with binocular indirect ophthalmoscopy
what are myelinated nerve fibres and how do they form
what do they look like
which types of patients are they more common in
asymptomatic
non progressive
myelination of the RGC axons that starts post lamina cribrosa and due to a mis-messaging of oligodendrocytes, this myelination continues into the retina
look like dense white feathers lesion which follows the course of the retinal nerve fibres
maybe more common in down’s syndrome or in patients with neurofibromatosis
what are myelinated nerve fibres often mistaken for/ddx
and what differentiates this from its ddx
what is your management
mistaken for cotton wool spots
but myelinated fibres are whiter, larger and denser and almost always adjacent to the optic disc
do not refer this patient if there is nothing of concern
what is papilloedema
what is it secondary to
bilaterally swollen optic discs - due to blockage of retrograde axoplasmic transport
secondary to raised inter cranial pressure
list the 6 possible symptoms of papilloedema
- possibly none
- transient obscuration of vision (TIA) with postural changes - move head to change ICP
- diplopia - 6th nerve paresis
- visual acuity only usually affected in terminal stages
- headaches
- nausea, vomiting
what are the 3 signs of early papilloedema
what are the 4 signs of established papilloedema
what is your management
Early
- mild disc swelling and hyperaemia (nasal margins affected first)
- blurring of disc margins
- venous engorgement = redness of disc
Established
- disc swelling
- cotton wool spots
- retinal folds
- hard exudates
management = refer this patient immediately to the Hes - to investigate what this papilloedema is secondary to
what is optic atrophy and what are the 2 types
irreversible degeneration of the optic nerve
primary or secondary
what is the primary type of optic atrophy and what is it called
- not associated with another disease
- hereditary optic atrophy
- Leber’s hereditary optic atrophy
what is the secondary type of optic atrophy and what can be the causes
- associated with another disease
e. g. px may have had raised ICP and papilloedema, treatment started too late and after it settled down the px will have permanent damage to the optic nerve - alcohol/tobacco
- drug induced
what is the sign/appearance of optic atrophy
what are the 4 main symptoms
what is the management
pale disc and nrr atrophy as no axons are functioning
symptoms:
- progressive loss of vision
- colour vision
- visual fields
- visual acuity
all affected
management:
if not noted previously, refer to Hes - speed depends on vision and whether its progressive or not
what is optic neuritis
what 2 types are there and what are the causes of each type
inflammation of the optic nerve
idiopathic - isolated sporadic incidence
demyelination
para-infectious:
- viral infection
- immunisation
infectious:
- cat scratch fever
- syphilis
- AIDS
- herpes zoster
what are the 6 signs of demyelinating optic neuritis
unilateral visual loss
- v/a 6/18 to 6/60 or even NLP
discomfort on eye movements
dyschromatopsia - R/G colour defects
visual fields defect
- loss in central field due to centrocaecal type vf loss
RAPD
- due to impaired conduction of nerve
normal appearance of optic nerve head because its retrobulbar
- occasionally papilitis
what is the prognosis of demyelinating optic neuritis
what is a drawback to the prognosis
what is the purpose of treatment
what is the optometric management
recovery
- begins within 2-3 weekend maximal after 6 months
- 75% recover visual acuity of 6/9 or better
but disease is characterised by relapses if its secondary to a demyelinating disease e.g. MS
treatment may delay further relapses
refer to casualty unless associated with demyelination - but is they’re established with MS you can just let their physician know
what is anterior ischaemic optic neuropathy
what is it caused by
what are the 2 types
what vf defect does it usually have
an infarct of the optic nerve head
caused by occlusion of the short posterior ciliary arteries (which supplies the retrobulbar ON with nutrients)
2 types:
non-arteritic
- more common
- not associated with arteritis
arteritic
- less common
- associated with arteritis
usually altitudinal hemianopia which respects the horizontal midline
which types of patients will suffer from a non-arteritic AION
what symptom will they present with
what will the the appearance of their optic disc
males aged 55-70 y/o
presents with sudden painless loss of vision
pale swollen disc with unclear margins
with surrounding disc haemorrhages
(due to the infarct of the short posterior ciliary arteries)
what are the 3 risk factors of non-arteritic AION
what is the prognosis
what is your management
‘at risk’ disc = all absent cup and disc, so nerves leaving the eye are congested and so can easily get occlusion of the posterior ciliary artery
hypertension
arteriosclerosis
prognosis:
no treatment possible
30% lose vision in other eye within two years (so try to treat systemic disease soon)
refer to casualty - arteritis needs to be excluded (as we can’t be sure if its arteritic or non-arteritic)
what is the symptoms of arteritic AION
what may this be preceded by
what age group does this occur in
sudden profound unilateral loss of vision
may have episodes of a TIA before the AION
between 60-70 y/o
what are the 8 symptoms of temporal arteritis
and what is it caused by
temporal headaches neck ache or stiffness jaw claudication malaise weight loss morning stiffness depression tender inflamed ocular arteritis
caused by AION
what is the management of temporal arteritis and what is the risk
what 3 things are done in hospital to treat temporal arteritis
what is the prognosis
ophthalmic emergency - as theres a risk of visual loss in the other eye and cerebral vascular account (as its inflamed arteries it can be anywhere in the body)
in hospital:
- temporal artery biopsy
- erythrocyte sedimentation (ESR)
- treated with high doses of oral steroids
visual acuity dos not recover
