Optic nerve anomalies and neuropathies

Question 1

what is a optic nerve disease defined as

Answer 1

a disease which involves damage to the retinal ganglion cell axons

Question 2

list the 4 symptoms of a optic nerve disease

Answer 2

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)

Question 3

what are the 4 clinical signs of optic nerve damage

Answer 3

RAPD - impaired/retarded conduction of the ON in diseased eye

Reduced contrast sensitivity

Visual field defects

Colour vision impairment - reg/green and asymmetrical

Question 4

list the 4 types of visual fields defects that can occur from optic nerve damage

and what does each one depend on

Answer 4

central

centrocaecal

arcuate

altitudinal

depends where in the optic pathway that the lesion is

Question 5

how can you detect a colour vision impairment on a patient who has optic nerve damage

Answer 5

by testing colour vision in each eye separately rather than bilaterally

Question 6

which 4 signs of optic nerve damage can be picked up by careful evaluation of ophthalmoscopy

Answer 6

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

Question 7

what are the 2 classifications of optic nerve anomalies

Answer 7

congenital

or

acquired

Question 8

list the 7 types of congenital optic nerve anomalies

Answer 8

hypoplasia 
coloboma
optic disc pit 
tilted disc 
drusen
glial remnants 
myelinated fibres

Question 9

list the 4 types of acquired optic nerve anomalies

Answer 9

papilloedema
optic atrophy
optic neuritis
AION

Question 10

what is optic nerve hypoplasia

how does it look

what 2 causes may it be associated with

Answer 10

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

Question 11

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

Answer 11

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)

Question 12

what 2 things can you do for management of optic nerve hypoplasia

Answer 12

if associated with astigmatism - correct refractive errors to avoid amblyopia

refer px if not already been investigated - because may have systemic associations

Question 13

what is a optic disc coloboma

how does the disc appear to look

what is the inheritance type

Answer 13

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

Question 14

list the appearance of a optic disc coloboma (4)

Answer 14

• 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

Question 15

what is the symptom of a optic disc coloboma

what else may it be associated with

what is the ddx

Answer 15

va may be affected depending on the severity

may be associated with neurological defects

ddx = glaucoma

Question 16

list 3 things that you will do as management of an optic disc coloboma

Answer 16

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

Question 17

list 3 optic disc coloboma complications and which speed of referral is required for each

Answer 17

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

Question 18

what is a optic disc pit

what appearances can they have

where abouts in the disc is it most commonly found

Answer 18

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

Question 19

what does a optic disc pit represent

Answer 19

the herniation of rudimentary neuroectoderm tissue

Question 20

what are the complications of a optic disc pit

Answer 20

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

Question 21

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

Answer 21

from a temporal optic disc

metamorphopsia/distortion in their vision

refer the px soon to the hospital

Question 22

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

Answer 22

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)

Question 23

what is the cause and appearance of congenital tilted disc syndrome

what else is it associated with

Answer 23

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

Question 24

what is the complications of titled disc syndrome

Answer 24

bitemporal superior quadrantonopia (as nasal fibres damaged)
as both eyes are affected

chiasmal lesions will respect the midline

Question 25

what is optic disc drusen how does it develop what is the prevalence

Answer 25

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

Question 26

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

Answer 26

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

Question 27

what is a glial remnant of the optic disc what will it look like and how can it be seen

Answer 27

remnant of the hyaloid artery = birdsmeisters papilla a white sheath will be floating in the vitreous best seen with binocular indirect ophthalmoscopy

Question 28

what are myelinated nerve fibres and how do they form what do they look like which types of patients are they more common in

Answer 28

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

Question 29

what are myelinated nerve fibres often mistaken for/ddx and what differentiates this from its ddx what is your management

Answer 29

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

Question 30

what is papilloedema what is it secondary to

Answer 30

bilaterally swollen optic discs - due to blockage of retrograde axoplasmic transport secondary to raised inter cranial pressure

Question 31

list the 6 possible symptoms of papilloedema

Answer 31

- 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

Question 32

what are the 3 signs of early papilloedema what are the 4 signs of established papilloedema what is your management

Answer 32

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

Question 33

what is optic atrophy and what are the 2 types

Answer 33

irreversible degeneration of the optic nerve primary or secondary

Question 34

what is the primary type of optic atrophy and what is it called

Answer 34

- not associated with another disease - hereditary optic atrophy - Leber's hereditary optic atrophy

Question 35

what is the secondary type of optic atrophy and what can be the causes

Answer 35

- 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

Question 36

what is the sign/appearance of optic atrophy what are the 4 main symptoms what is the management

Answer 36

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

Question 37

what is optic neuritis what 2 types are there and what are the causes of each type

Answer 37

inflammation of the optic nerve idiopathic - isolated sporadic incidence demyelination para-infectious: - viral infection - immunisation infectious: - cat scratch fever - syphilis - AIDS - herpes zoster

Question 38

what are the 6 signs of demyelinating optic neuritis

Answer 38

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

Question 39

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

Answer 39

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

Question 40

what is anterior ischaemic optic neuropathy what is it caused by what are the 2 types what vf defect does it usually have

Answer 40

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

Question 41

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

Answer 41

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)

Question 42

what are the 3 risk factors of non-arteritic AION what is the prognosis what is your management

Answer 42

'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)

Question 43

what is the symptoms of arteritic AION what may this be preceded by what age group does this occur in

Answer 43

sudden profound unilateral loss of vision may have episodes of a TIA before the AION between 60-70 y/o

Question 44

what are the 8 symptoms of temporal arteritis and what is it caused by

Answer 44

``` temporal headaches neck ache or stiffness jaw claudication malaise weight loss morning stiffness depression tender inflamed ocular arteritis ``` caused by AION

Question 45

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

Answer 45

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