Optic nerve anomalies and neuropathies Flashcards Preview

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Flashcards in Optic nerve anomalies and neuropathies Deck (45)
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1

what is a optic nerve disease defined as

a disease which involves damage to the retinal ganglion cell axons

2

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)

3

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

4

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

5

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

6

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

7

what are the 2 classifications of optic nerve anomalies

congenital

or

acquired

8

list the 7 types of congenital optic nerve anomalies

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

9

list the 4 types of acquired optic nerve anomalies

papilloedema
optic atrophy
optic neuritis
AION

10

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

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

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)

12

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

13

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

14

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

15

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

16

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

17

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

18

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

19

what does a optic disc pit represent

the herniation of rudimentary neuroectoderm tissue

20

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

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

from a temporal optic disc

metamorphopsia/distortion in their vision

refer the px soon to the hospital

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

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)

23

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

24

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

25

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

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

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

27

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

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

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

29

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

30

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