OPT 311 Optic Nerve

What are 4 potential causes of non-glaucomatous ON cupping?

ischemia = e.g. ischemic optic neuropathy

compression = e.g. a tumor pushing on the chiasm

inflam = e.g. demyelinating disease

trauma = e.g. traumatic optic neuropathy after getting hit in the eye

Is cupping of the ONH glaucoma if the ONH rim is pale?

no = rim pallor is most likely neuro disease

Is cupping of the ONH glaucoma if the ONH rim is gone/thin?

yes = rim thinning is glaucoma

Is cupping of the ONH glaucoma if the ONH rim is sharpened?

yes = BV bayonetting is glaucomatous

What are some causes of a pale ONH?

ONH hypoplasia

myopia

aphakia

optic atrophy

infants

What 3 findings will we always see in true optic atrophy?

pale nerve head

reduced VA

APD

dyschromatopsia

VF defect

RNFL dropout

electrodiagnostic dropout

What is the cause of this pale ONH?

hypoplastic ONH = part of sclera is filling optic canal around the ONH

Through NS CATs, a pale ONH may look ___________.

reddish

Through dim illumination or an undilated pupil, a pale ONH may look __________, which is why it's important to assess the ONH on bright illumination.

pink

What is ascending optic atrophy?

AKA secondary optic atrophy = lesion in the ganglion cells or ONH or due to RP = BLURRY disc margins, artery attenuation or absence, sheathed BV

What are some causes of ascending optic atrophy?

papillitis

chronic papilledema

periarteritis

CRAO

AAION

POAG

What cause of ascending optic atrophy is shown here?

AAION

What cause of ascending optic atrophy is shown here?

RP

What cause of ascending optic atrophy is shown here?

chronic atrophic papilledema

What is descending optic atrophy?

AKA primary optic atrophy = lesion in the LGN to the ONH = SHARP disc margins, normal BV

What are some causes of descending optic atrophy?

retrobulbar optic neuritis

toxic neuropathy

trauma

neoplasms in the orbit, canal, cranium (compression)

What cause of descending optic atrophy is seen here?

neoplasm in cranium (craniopharyngioma) causing compression

What cause of descending optic atrophy is seen here?

intracranial injury to ON

What is the challenge with diffuse ONH pallor?

difficult to ascertain cause = could be due to CRAO, canalicular meningioma, hypotensive events, etc.

What typically causes temporal segmental ONH pallor?

toxic disease = alcohol, malnutrition

hereditary degeneration = Leber's optic atrophy, autosomal dominant optic atrophy, etc.

acute demyelinating disease

compressive disease

What retinal and VF area is associated with temporal segmental ONH pallor?

papillomacular bundle is involved = cecocentral VF defect from blindspot to fixation

What typically causes inferior wedge-shaped segmental ONH pallor?

glaucoma

What typically causes superior wedge-shaped segmental ONH pallor?

ischemic optic neuropathy

What typically causes "bow tie" segmental ONH pallor?

optic tract lesions = carry ipsilateral temporal fibers and contralateral nasal fibers

optic chiasm lesions = bilateral bow tie

Ex) if you lesion the left optic tract, which retinal fibers are affected?

fibers from temporal retina entering OS ONH

fibers from nasal retina entering OD ONH

papillomacular bundles of the OD ONH

Ex) if you lesion the left optic tract, which ONH areas are affected?

bow tie pallor in OD ONH

temporal pallor in OS ONH

What typically causes altitudinal segmental ONH pallor?

NAAION or AAION = ischemic event like a local infarction of the post ciliary arteries

What is the Hoyt-Spencer sign?

acquired optociliary shunt BV on a pale ONH with slow progression vision loss

What are some possible causes of acquired optociliary shunt BV?

sphenoid wing meningiomas

ON gliomas

ON arachnoid cysts

chronic OAG

ON drusen

CRAO

chronic papilledema

DM

What finding shown here is a cause of pseudo disc edema?

glial veil

What finding shown here is a cause of pseudo disc edema?

myelinated nerve fibers

What finding shown here is a cause of pseudo disc edema?

CWS near the ONH

What finding shown here is a cause of pseudo disc edema?

flame-shaped hemorrhages near the ONH with CWS

What finding shown here is a cause of pseudo disc edema?

drusen of the ONH

What finding shown here is a cause of pseudo disc edema?

giant hamartoma of the ONH

What finding shown here is a cause of pseudo disc edema?

hypoplastic ONH – vessels seem out of proportion to the size of the ONH

What finding shown here is a cause of true disc edema?

papilledema due to IIH

NOTE: papilledema is just 1 cause of disc edema

What finding shown here is a cause of true disc edema?

papillitis with disc edema and good vision

What finding shown here is a cause of true disc edema?

idiopathic scarring of ONH

What finding shown here is a cause of true disc edema?

BRVO = venous stasis retinopathy with edema, hemes

What finding shown here is a cause of true disc edema?

grade 4 HTN retinopathy causing disc edema

What finding shown here is a cause of true disc edema?

AAION causing disc edema, flame hemes

What is a giant hamartoma of the ONH?

mineralized hamartoma, closely related to ON astrocytic hamartoma, often found in tuberous sclerosis pt's

What are disc drusen?

hyaline, acellular, calcium phosphate byproducts of disc astrocytes (may or may not be calcified)

How can we differentiate papilledema from drusen based on the cup?

papilledema = present

drusen = absent

How can we differentiate papilledema from drusen based on the disc margins?

papilledema = blurred sup and inf

drusen = symmetric, scalloped blur

How can we differentiate papilledema from drusen based on the colour?

papilledema = hyperemic

drusen = normal

How can we differentiate papilledema from drusen based on the NRR?

papilledema = elevated rim that extends into RNFL

drusen = central elevation, bumpy

How can we differentiate papilledema from drusen based on the RNFL?

papilledema = edema sup and inf, muddy peripapillary reflex

drusen = focal atrophy, normal linear light reflexes

How can we differentiate papilledema from drusen based on the BV?

papilledema = optociliary shunts develop, venous dilation, absent SVP

drusen = central origin, trifurcation and other anomalous patterns, present SVP

Why MIGHT there no SVP in disc edema?

elevated ICP > 200mmH2O

NOTE: pt may not have had an SVP to begin with, so this isn't always the best rule of thumb!

How can we better visualize disc drusen on fundoscopy?

retroilluminate the ONH by putting the beam right beside it

red-free filter

True or False: drusen of the ONH are the most common congenital/inherited optic neuropathy.

true

How do disc drusen appear on FAF?

hyperAF drusen within the hypoAF nerve head

How can we differentiate papilledema from drusen with OCT?

papilledema = rounded, regular elevation +/- lazy V sign

drusen = irregular elevation

How do disc drusen appear on B scan?

hyper-reflective if calcified

How do disc drusen appear on a CT scan?

hyper-reflective if calcified

How can drusen progress anatomically over time?

buried drusen may migrate to the surface of the ONH

How can drusen progress functionally over time?

VF defects may develop, including an enlarged blindspot and arcuate defect

True or False: drusen and papilledema will not coexist at the same time in a pt.

false

How do surface drusen appear on early IVFA?

blockage

How do surface drusen appear on late IVFA?

nodular staining

How do buried drusen appear on early IVFA?

no staining or nodular staining

How do buried drusen appear on late IVFA?

late peripapillary staining (noduler, circumferential)

How does disc edema appear on IVFA?

early and late diffuse leakage

How does co-existent drusen and edema appear on IVFA?

early = edema leaks, drusen stain

late = edema leaks, drusen stain

What are 2 features of the disc margin that suggests it may be a hypoplastic ONH?

double ring sign = outer yellow sclera, inner pigmented ring around ONH

margins may be blurred due to too many crowded axons

NOTE: these findings are not that common

Double ring sign may result in you _______________________ the nerve size.

overestimating

A hypoplastic disc actually has a subnormal number of _________, but it has a normal number of ____________________________________________.

subnormal axons

normal mesodermal glial elements

What feature of the NRR and RNFL suggests it may be a hypoplastic ONH?

RNFL is often thin/absent due to either axon atrophy or RGCs failing to develop

What feature of the disc colour suggests it may be a hypoplastic ONH?

pale colour bc the sclera is showing through

red colour bc the small disc is in high contrast to the surround

What feature of the disc BV suggests it may be a hypoplastic ONH?

tortuous, large in comparison to the nerve itself

Can VF defects result from hypoplastic ONH?

yes

What is the most common VF defect we see in hypoplastic ONH?

most often as bitemporal hemianopsias but can be other defects anywhere in the VF, including binasal or ST defects

True or False: hypoplastic discs may cause a VF defect that does NOT respect the vertical midline.

true

What are some associations seen in pt's with bilateral hypoplasia of their ONH and poor VA?

developmental abnormalities like GH deficiency, hypothyroidism

forebrain anomalies such as lacking a septum pelucidum between the 2 lateral ventricle halves

How should we manage pt's with bilateral hypoplasia of their ONH and poor VA?

refer to pediatrician to assess:

GH levels

thyroid function

endocrine function

CT/MRI to look for basal encephalocoele = abnormal communication of bone that allows brain tissue to herniate into orbit, nasal pharynx, etc

How do we manage pt's with bilateral hypoplasia of their ONH and good VA?

no management necessary other than routine following with an OD/OMD and pediatrician to monitor for endocrine issues

How do we manage pt's with unilateral hypoplasia of their ONH and good OR poor VA?

no management necessary other than routine following with an OD/OMD and pediatrician to monitor for endocrine/neuro issues

What is De Morsier's syndrome?

septo-optic dysplasia with...

bilateral ONH dyplasia

absence of septum pellucidum

agenesis of corpus callosum

dysplasia of 3rd ventricle

hypopitutitarism

What are 4 other congenital nerve disorders than may be associated with forebrain anomalies?

ON aplasia/dysplasia

ONH pit

sup segmental hypoplasia

ONH coloboma

What is Kallman's syndrome?

hypoplastic ONH

anosmia

forebrain anomalies

gonadotropin deficiency = delayed puberty, amenorrhea