optic neuropathy 1 Flashcards
how many retinal ganglion cell axons make up the optic nerve?
1-1.5 million
what are the 4 anatomical segments and sizes of the optic nerve?
4 anatomical segments Intraocular: 1 mm Intraorbital: 25 mm Intracanalicular: 10 mm Intracranial: 16 mm
vascular insult
intraocular
muscle engorgement/tumors
intraorbital
fractures and sinus inflammation
intracanalicular
pituitary gland and circle of willis
intracranial
where are the cell bodies of retinal ganglion cells?
ganglion cell layer
is the optic nerve covered by meninges?
yes
what supplies the optic nerve prelaminar?
SPCA (peripapillary choroidal vessels); branch of opthalmic artery; branch of internal carotid
blood supply of lamina cribrosa
SPCA, circle of zin haller
blood supply of retrolaminar
branches from CRA, branches from pial vessels
blood supply of choroid
SPCA
what determines papillaedema?
bilateral optic nerve head swelling due to raised intracranial pressure
how can we tell difference b/w NV and shunts?
angiofluorescence; shuts do not leak and NV does
3 conditions that can cause collaterals/shunts
Optic nerve sheath meningioma
CRVO
Chronic glaucoma
VA loss RAPD Dyschromatopsia VF defect Reduced contrast sensitivity +/- normal optic disc appearance Abnormal VEP
optic nerve dysfunction
2 types of optic neuritis
Typical: demyelinating optic neuritis
Atypical: systemic infectious/inflammatory causes
5 hallmarks of typical optic neuritis
Primary demyelination of the optic nerve - Autoimmune: antibodies attack myelin sheath Sudden VA loss -Progresses over 1 week -Improvement begins by 1 month Pain on EOMs: 90% of patients +/- RAPD Dyschromatopsia: usually worse than VA